01-schema_spec.lua

local Schema = require "kong.db.schema"
local cjson  = require "cjson"
local helpers = require "spec.helpers"
local table_copy = require "kong.tools.table".deep_copy


local SchemaKind = {
  { name = "schema", new = Schema.new, },
  { name = "subschema", new = function(definition)
      local schema = assert(Schema.new({
        name = "test",
        subschema_key = "name",
        fields = definition.fields,
      }))
      assert(schema:new_subschema("subtest", definition))
      return assert(schema.subschemas["subtest"])
    end
  }
}


describe("schema", function()
  local uuid_pattern = "^" .. ("%x"):rep(8) .. "%-" .. ("%x"):rep(4) .. "%-"
                           .. ("%x"):rep(4) .. "%-" .. ("%x"):rep(4) .. "%-"
                           .. ("%x"):rep(12) .. "$"

  local function check_all_types_covered(fields)
    local covered = {}
    for _, item in ipairs(fields) do
      local field = item[next(item)]
      covered[field.type] = true
    end
    covered["foreign"] = true
    for name, _ in pairs(Schema.valid_types) do
      assert.truthy(covered[name], "type '" .. name .. "' not covered")
    end
  end

  describe("construction", function()

    it("fails if no definition is given", function()
      local Test, err = Schema.new()
      assert.falsy(Test)
      assert.string(err)
    end)

    it("fails if schema fields are not defined", function()
      local Test, err = Schema.new({ fields = nil })
      assert.falsy(Test)
      assert.string(err)
    end)


    it("fails on invalid foreign reference", function()
      local Test, err = Schema.new({
        fields = {
          { f = { type = "foreign", reference = "invalid_reference" } },
          { b = { type = "number" }, },
          { c = { type = "number" }, },
        }
      })
      assert.falsy(Test)
      assert.match("invalid_reference", err)
    end)

  end)

  describe("validate", function()

    it("orders validators", function()
      local validators_len = 0
      local validators_order_len = 0

      for _ in pairs(Schema.validators) do
        validators_len = validators_len + 1
      end

      for _ in pairs(Schema.validators_order) do
        validators_order_len = validators_order_len + 1
      end

      assert.equal(validators_len, validators_order_len)
    end)

    it("fails if given no input", function()
      local Test = Schema.new({ fields = {} })
      assert.has_error(function()
        Test:validate(nil)
      end)
    end)

    it("fails if given a bad field type", function()
      local Test = Schema.new({
        fields = {
          { foo = { type = "typo" }, },
        }
      })
      assert.falsy(Test:validate({ foo = "foo" }))
    end)

    it("validates a range with 'between'", function()
      local Test = Schema.new({
        fields = {
          { a_number = { type = "number", between = { 9.5, 20.5 } } }
        }
      })
      assert.truthy(Test:validate({ a_number = 15 }))
      assert.truthy(Test:validate({ a_number = 10 }))
      assert.truthy(Test:validate({ a_number = 20 }))
      assert.falsy(Test:validate({ a_number = 9.4 }))
      assert.falsy(Test:validate({ a_number = 20.9 }))
      assert.falsy(Test:validate({ a_number = "wat" }))
    end)

    it("forces a value with 'eq'", function()
      local Test = Schema.new({
        fields = {
          { a_number = { type = "number", eq = 9 } }
        }
      })
      assert.truthy(Test:validate({ a_number = 9 }))
      assert.falsy(Test:validate({ a_number = 8 }))
      assert.falsy(Test:validate({ a_number = "wat" }))
    end)

    it("'eq' accepts false", function()
      local Test = Schema.new({
        fields = {
          { a_boolean = { type = "boolean", eq = false } }
        }
      })
      assert.truthy(Test:validate({ a_boolean = false }))
      assert.falsy(Test:validate({ a_boolean = true }))
      assert.falsy(Test:validate({ a_boolean = "false" }))
    end)

    it("'eq' accepts null", function()
      local Test = Schema.new({
        fields = {
          { a_boolean = { type = "boolean", eq = ngx.null } }
        }
      })
      assert.truthy(Test:validate({ a_boolean = ngx.null }))
      -- null means unset, so not passing a value matches it
      assert.truthy(Test:validate({ a_boolean = nil }))
      assert.falsy(Test:validate({ a_boolean = "null" }))
    end)

    it("'eq' returns custom error message for null value", function()
      local Test = Schema.new({
        fields = {
          { a_null_array = {
            type = "array",
            elements = { type = "string" },
            eq = ngx.null,
            err = "cannot set value for this field",
          }}
        }
      })

      assert.truthy(Test:validate({ a_null_array = ngx.null }))
      local ok, err = Test:validate({ a_null_array = { "foo" }})
      assert.falsy(ok)
      assert.same("cannot set value for this field", err.a_null_array)
    end)

    it("'eq' returns default error message if no custom message is given", function()
      local Test = Schema.new({
        fields = {
          { a_null_array = {
            type = "array",
            elements = { type = "string" },
            eq = ngx.null,
          }}
        }
      })

      assert.truthy(Test:validate({ a_null_array = ngx.null }))
      local ok, err = Test:validate({ a_null_array = { "foo" }})
      assert.falsy(ok)
      assert.same("value must be null", err.a_null_array)
    end)

    it("'eq' returns custom error message for non-null values", function()
      local Test = Schema.new({
        fields = {
          { a_field = {
            type = "string",
            eq = "foo",
            err = "can only set this field to 'foo'",
          }}
        }
      })

      assert.falsy(Test:validate({ a_field = ngx.null }))
      local ok, err = Test:validate({ a_field = "bar" })
      assert.falsy(ok)
      assert.same("can only set this field to 'foo'", err.a_field)
    end)

    it("'ne' returns custom error message for null value", function()
      local Test = Schema.new({
        fields = {
          { a_null_array = {
            type = "array",
            elements = { type = "string" },
            ne = ngx.null,
            err = "cannot set this field to null",
          }}
        }
      })

      assert.truthy(Test:validate({ a_null_array = { "foo" }}))
      local ok, err = assert.falsy(Test:validate({ a_null_array = ngx.null }))
      assert.falsy(ok)
      assert.same("cannot set this field to null", err.a_null_array)
    end)

    it("'ne' returns custom error message for non-null values", function()
      local Test = Schema.new({
        fields = {
          { a_field = {
            type = "string",
            ne = "foo",
            err = "cannot set this field to 'foo'",
          }}
        }
      })

      assert.truthy(Test:validate({ a_field = ngx.null }))
      local ok, err = Test:validate({ a_field = "foo" })
      assert.falsy(ok)
      assert.same("cannot set this field to 'foo'", err.a_field)
    end)

    it("'ne' returns default error message if no custom message is given", function()
      local Test = Schema.new({
        fields = {
          { a_field = {
            type = "string",
            ne = "foo",
          }}
        }
      })

      assert.truthy(Test:validate({ a_field = ngx.null }))
      local ok, err = Test:validate({ a_field = "foo" })
      assert.falsy(ok)
      assert.same("value must not be foo", err.a_field)
    end)



    it("'eq' returns default error message if no custom message is given", function()
      local Test = Schema.new({
        fields = {
          { a_null_array = {
            type = "array",
            elements = { type = "string" },
            eq = ngx.null,
          }}
        }
      })

      assert.truthy(Test:validate({ a_null_array = ngx.null }))
      local ok, err = Test:validate({ a_null_array = { "foo" }})
      assert.falsy(ok)
      assert.same("value must be null", err.a_null_array)
    end)

    it("forces a value with 'gt'", function()
      local Test = Schema.new({
        fields = {
          { a_number = { type = "number", gt = 5 } }
        }
      })
      assert.truthy(Test:validate({ a_number = 6 }))
      assert.falsy(Test:validate({ a_number = 5 }))
      assert.falsy(Test:validate({ a_number = 4 }))
      assert.falsy(Test:validate({ a_number = "wat" }))
    end)

    it("validates arrays with 'contains'", function()
      local Test = Schema.new({
        fields = {
          { pirate = { type = "array",
                       elements = { type = "string" },
                       contains = "arrr",
                     },
          }
        }
      })
      assert.truthy(Test:validate({ pirate = { "aye", "arrr", "treasure" } }))
      assert.falsy(Test:validate({ pirate = { "let's do our taxes", "please" } }))
      assert.falsy(Test:validate({ pirate = {} }))
    end)

    it("makes sure all types run validators", function()
      local num = { type = "number" }
      local tests = {
        { { type = "array", elements = num, len_eq = 2 },
          { 10, 20, 30 } },
        { { type = "set", elements = num, len_eq = 2 },
          { 10, 20, 30 } },
        { { type = "string", len_eq = 2 },
          "foo" },
        { { type = "number", between = { 1, 3 } },
          4 },
        { { type = "integer", between = { 1, 3 } },
          4 },
        { { type = "map" },     -- no map-specific validators
          "fail" },
        { { type = "record" },  -- no record-specific validators
          "fail" },
        { { type = "boolean" }, -- no boolean-specific validators
          "fail" },
        { { type = "function" },
          "fail" },
        { { type = "json", json_schema = { inline = { type = "string" }, } },
          123 },
      }

      local covered_check = {}
      for i, test in pairs(tests) do
        table.insert(covered_check, { ["a"..tostring(i)] = test[1] })
        local Test = Schema.new({
          fields = {
            { x = test[1] }
          }
        })
        local ret, errs = Test:validate({ x = test[2] })
        local case_msg = "Error case: "..test[1].type
        assert.falsy(ret, case_msg)
        assert.truthy(errs["x"], case_msg)
      end
      check_all_types_covered(covered_check)
    end)

    it("validates a pattern with 'match'", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "string", match = "^%u+$" } }
        }
      })
      assert.truthy(Test:validate({ f = "HELLO" }))
      assert.truthy(Test:validate({ f = "O" }))
      assert.falsy(Test:validate({ f = "" }))
      assert.falsy(Test:validate({ f = 1 }))
    end)

    it("validates an anti-pattern with 'not_match'", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "string", not_match = "^%u+$" } }
        }
      })
      assert.truthy(Test:validate({ f = "hello" }))
      assert.truthy(Test:validate({ f = "o" }))
      assert.falsy(Test:validate({ f = "HELLO" }))
      assert.falsy(Test:validate({ f = 1 }))
    end)

    it("validates one pattern among many with 'match_any'", function()
      local Test = Schema.new({
        fields = {
          { f = {
              type = "string",
              match_any = {
                patterns = { "^hello", "world$" },
              }
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = "hello Earth" }))
      assert.truthy(Test:validate({ f = "goodbye world" }))
      assert.falsy(Test:validate({ f = "hi universe" }))
      assert.falsy(Test:validate({ f = 1 }))
    end)

    it("'match_any' produces custom messages", function()
      local Test2 = Schema.new({
        fields = {
          { f = {
              type = "string",
              match_any = {
                patterns = { "^hello", "world$" },
                err = "custom message",
              }
            }
          }
        }
      })
      local ok, err = Test2:validate({ f = "hi universe" })
      assert.falsy(ok)
      assert.same({ f = "custom message" }, err)
    end)

    it("validates all patterns in 'match_all'", function()
      local Test = Schema.new({
        fields = {
          { f = {
              type = "string",
              match_all = {
                { pattern = "^hello" },
                { pattern = "world$" },
              }
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = "helloworld" }))
      assert.truthy(Test:validate({ f = "hello crazy world" }))
      assert.falsy(Test:validate({ f = "hello universe" }))
      assert.falsy(Test:validate({ f = "goodbye world" }))
      assert.falsy(Test:validate({ f = "hi universe" }))
      assert.falsy(Test:validate({ f = 1 }))
    end)

    it("'match_all' produces custom messages", function()
      local Test2 = Schema.new({
        fields = {
          { f = {
              type = "string",
              match_all = {
                { pattern = "^hello", err = "error 1" },
                { pattern = "world$", err = "error 2" },
              }
            }
          }
        }
      })
      local ok, err = Test2:validate({ f = "hi universe" })
      assert.falsy(ok)
      assert.same({ f = "error 1" }, err)
      ok, err = Test2:validate({ f = "hello universe" })
      assert.falsy(ok)
      assert.same({ f = "error 2" }, err)
    end)

    it("validates all anti-patterns in 'match_none'", function()
      local Test = Schema.new({
        fields = {
          { f = {
              type = "string",
              match_none = {
                { pattern = "^hello" },
                { pattern = "world$" },
              }
            }
          }
        }
      })
      assert.falsy(Test:validate({ f = "helloworld" }))
      assert.falsy(Test:validate({ f = "hello crazy world" }))
      assert.falsy(Test:validate({ f = "hello universe" }))
      assert.falsy(Test:validate({ f = "goodbye world" }))
      assert.truthy(Test:validate({ f = "hi universe" }))
    end)

    it("'match_none' produces custom messages", function()
      local Test2 = Schema.new({
        fields = {
          { f = {
              type = "string",
              match_none = {
                { pattern = "^hello", err = "error 1" },
                { pattern = "world$", err = "error 2" },
              }
            }
          }
        }
      })
      local ok, err = Test2:validate({ f = "hello universe" })
      assert.falsy(ok)
      assert.same({ f = "error 1" }, err)
      ok, err = Test2:validate({ f = "goodbye world" })
      assert.falsy(ok)
      assert.same({ f = "error 2" }, err)
    end)

    it("validates an array length with 'len_eq'", function()
      local Test = Schema.new({
        fields = {
          {
            arr = {
              type = "array",
              elements = { type = "number" },
              len_eq = 3
            },
          },
        }
      })
      assert.truthy(Test:validate({ arr = { 1, 2, 3 }}))
      assert.falsy(Test:validate({ arr = { 1 }}))
      assert.falsy(Test:validate({ arr = { 1, 2, 3, 4 }}))
    end)

    it("validates an array and a set is sequentical", function()
      local Test = Schema.new({
        fields = {
          { set = { type = "set",   elements = { type = "number" } } },
          { arr = { type = "array", elements = { type = "number" } } },
        }
      })

      local tests = {
        [{}]                       = true,
        [{ 1 }]                    = true,
        [{ nil, 1 }]               = false,
        [{ 1, 2, 3 }]              = true,
        [{ 1, 2, 3, nil }]         = true,
        [{ 1, 2, 3, nil, 4, nil }] = false
      }

      for t, result in pairs(tests) do
        local fields = Test:process_auto_fields({
          arr = t,
          set = t,
        })

        if result then
          assert.truthy(Test:validate(fields))
        else
          assert.falsy(Test:validate(fields))
        end
      end
    end)

    it("validates a set length with 'len_eq'", function()
      local Test = Schema.new({
        fields = {
          {
            set = {
              type = "set",
              elements = { type = "number" },
              len_eq = 3
            },
          }
        }
      })
      local function check(set)
        set = Test:process_auto_fields(set)
        return Test:validate(set)
      end
      assert.truthy(check({ set = { 4, 5, 6 }}))
      assert.truthy(check({ set = { 4, 5, 6, 4 }}))
      assert.falsy(check({ set = { 4, 4, 4 }}))
      assert.falsy(check({ set = { 4, 5 }}))
    end)

    it("validates a string length with 'len_min'", function()
      local Test = Schema.new({
        fields = {
          { s = { type = "string", len_min = 1 }, },
        }
      })
      assert.truthy(Test:validate({ s = "A" }))
      assert.truthy(Test:validate({ s = "AAAAA" }))
      assert.falsy(Test:validate({ s = "" }))
    end)

    it("strings cannot be empty unless said otherwise", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "string" }, },
          { b = { type = "string", len_min = 0 }, },
        }
      })
      assert.truthy(Test:validate({ a = "AA", b = "AA" }))
      assert.truthy(Test:validate({ a = "A", b = "A" }))
      assert.truthy(Test:validate({ a = "A", b = "" }))
      local ok, errs = Test:validate({ a = "", b = "" })
      assert.falsy(ok)
      assert.string(errs["a"])
      assert.falsy(errs["b"])
    end)

    it("validates a string length with 'len_max'", function()
      local Test = Schema.new({
        fields = {
          { s = { type = "string", len_min = 1 }, },
        }
      })
      assert.truthy(Test:validate({ s = "A" }))
      assert.truthy(Test:validate({ s = "AAAAA" }))
      assert.falsy(Test:validate({ s = "" }))
    end)

    it("validates a timestamp with 'timestamp'", function()
      local Test = Schema.new({
        fields = {
          { a_number = { type = "number", timestamp = true } }
        }
      })
      for _, n in ipairs({ 1, 1234567890, 9876543210 }) do
        assert.truthy(Test:validate({ a_number = n }))
      end
      for _, n in ipairs({ -1, 0, "wat" }) do
        assert.falsy(Test:validate({ a_number = n }))
      end
    end)

    it("validates the shape of UUIDs with 'uuid'", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "string", uuid = true } }
        }
      })

      local tests = {
        -- correct
        { "truthy", "cbb297c0-a956-486d-ad1d-f9b42df9465a" },
        -- invalid variant, but accepts
        { "truthy", "cbb297c0-a956-486d-dd1d-f9b42df9465a" },
        -- "null" UUID
        { "truthy", "00000000-0000-0000-0000-000000000000" },
        -- incorrect characters
        { "falsy", "cbb297c0-a956-486d-ad1d-f9bZZZZZZZZZ" },
        -- no dashes
        { "falsy", "cbb297c0a956486dad1df9b42df9465a" },
      }
      for _, test in ipairs(tests) do
        assert[test[1]](Test:validate({ f = test[2] }))
      end
    end)

    it("validates mutually exclusive set values", function()
      local Test = Schema.new({
        fields = {
          { f = {
            type = "array",
            elements = { type = "string", one_of = {"v1", "v2", "v3", "v4"} },
            mutually_exclusive_subsets = { {"v1", "v3"}, {"v2", "v4"} },
          }}
        }
      })

      local tests = {
        -- valid
        {"truthy", {}},
        {"truthy", {"v1"}},
        {"truthy", {"v2"}},
        {"truthy", {"v1", "v3"}},
        {"truthy", {"v2", "v4"}},
        -- invalid
        {"falsy", {"v1", "v2"}},
        {"falsy", {"v1", "v4"}},
        {"falsy", {"v3", "v2"}},
        {"falsy", {"v3", "v4"}},
      }

      for _, test in ipairs(tests) do
        assert[test[1]](Test:validate({ f = test[2] }))
      end
    end)

    it("ensures an array is a table", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "array", elements = { type = "string" } } }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.falsy(Test:validate({ f = "foo" }))
    end)

    it("validates array elements", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "array", elements = { type = "number" } } }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.truthy(Test:validate({ f = {1} }))
      assert.truthy(Test:validate({ f = {1, -1} }))
      assert.falsy(Test:validate({ f = {"hello"} }))
      assert.falsy(Test:validate({ f = {1, 2, "foo"} }))
    end)

    it("validates rules in array elements", function()
      local Test = Schema.new({
        fields = {
          {
            f = {
              type = "array",
              elements = {
                type = "string",
                one_of = { "foo", "bar", "baz" },
                not_one_of = { "forbidden", "also_forbidden" },
              }
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.truthy(Test:validate({ f = {"foo"} }))
      assert.truthy(Test:validate({ f = {"baz", "foo"} }))
      assert.falsy(Test:validate({ f = {"hello"} }))
      assert.falsy(Test:validate({ f = {"foo", "hello", "foo"} }))
      assert.falsy(Test:validate({ f = {"baz", "foo", "forbidden"} }))
      assert.falsy(Test:validate({ f = {"baz", "foo", "also_forbidden"} }))
    end)

    it("ensures a set is a table", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "set", elements = { type = "string" } } }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.falsy(Test:validate({ f = "foo" }))
    end)

    it("validates set elements", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "set", elements = { type = "number" } } }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.truthy(Test:validate({ f = {1} }))
      assert.truthy(Test:validate({ f = {1, -1} }))
      assert.falsy(Test:validate({ f = {"hello"} }))
      assert.falsy(Test:validate({ f = {1, 2, "foo"} }))
    end)

    it("validates set elements", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "set", elements = { type = "number" } } }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.truthy(Test:validate({ f = {1} }))
      assert.truthy(Test:validate({ f = {1, -1} }))
      assert.falsy(Test:validate({ f = {"hello"} }))
      assert.falsy(Test:validate({ f = {1, 2, "foo"} }))
    end)

    it("ensures a map is a table", function()
      local Test = Schema.new({
        fields = {
          {
            f = {
              type = "map",
              keys = { type = "string" },
              values = { type = "string" },
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.falsy(Test:validate({ f = "foo" }))
    end)

    it("accepts a map with `keys` and `values`", function()
      local Test = Schema.new({
        fields = {
          {
            f = {
              type = "map",
              keys = { type = "string" },
              values = { type = "string" },
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
    end)

   it("validates map elements", function()
      local Test = Schema.new({
        fields = {
          {
            f = {
              type = "map",
              keys = { type = "string" },
              values = { type = "number" },
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = { foo = 2 } }))
      assert.falsy(Test:validate({ f = { [2] = 2 } }))
      assert.falsy(Test:validate({ f = { [2] = "foo" } }))
      assert.falsy(Test:validate({ f = { foo = "foo" } }))
      assert.truthy(Test:validate({ f = { bar = 3, foo = 2 } }))
      assert.falsy(Test:validate({ f = { bar = 3, [2] = 2 } }))
      assert.falsy(Test:validate({ f = { bar = 3, [2] = "foo" } }))
      assert.falsy(Test:validate({ f = { bar = 3, foo = "foo" } }))
    end)

    it("ensures a record is a table", function()
      local Test = Schema.new({
        fields = {
          {
            f = {
              type = "record",
              fields = { r = { type = "string" } },
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
      assert.falsy(Test:validate({ f = "foo" }))
    end)

    it("accepts a record with empty `fields`", function()
      local Test = Schema.new({
        fields = {
          {
            f = {
              type = "record",
              fields = {},
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = {} }))
    end)

   it("validates record elements", function()
      local Test = Schema.new({
        fields = {
          {
            f = {
              type = "record",
              fields = {
                { a = { type = "string" }, },
                { b = { type = "number" }, },
              },
            }
          }
        }
      })
      assert.truthy(Test:validate({ f = { a = "foo" } }))
      assert.truthy(Test:validate({ f = { b = 42 } }))
      assert.truthy(Test:validate({ f = { a = "foo", b = 42 } }))
      assert.falsy(Test:validate({ f = { a = 2 } }))
      assert.falsy(Test:validate({ f = { b = "foo" } }))
      assert.falsy(Test:validate({ f = { a = 2, b = "foo" } }))
    end)

   it("validates nested records", function()
      local Test = Schema.new({
        fields = {
          { f = {
              type = "record",
              fields = {
                { r = {
                    type = "record",
                    fields = {
                      { a = { type = "string" } },
                      { b = { type = "number" } } }}}}}}}})
      assert.truthy(Test:validate({ f = { r = { a = "foo" }}}))
      assert.truthy(Test:validate({ f = { r = { b = 42 }}}))
      assert.truthy(Test:validate({ f = { r = { a = "foo", b = 42 }}}))
      assert.falsy(Test:validate({ f = { r = { a = 2 }}}))
      assert.falsy(Test:validate({ f = { r = { b = "foo" }}}))
      assert.falsy(Test:validate({ f = { r = { a = 2, b = "foo" }}}))
    end)

    it("validates shorthands type check with nested records", function()
      local Test = Schema.new({
        fields = {
          { r = {
              type = "record",
              fields = {
                { a = { type = "string" } },
                { b = { type = "number" } } },
              shorthand_fields = {
                {
                  username = {
                    type = "string",
                    func = function(value)
                      return {
                        b = value
                      }
                    end,
                  }}}}}}})
      local input =  { r = { username = 123 }}
      local ok, err = Test:process_auto_fields(input)
      assert.falsy(ok)
      assert.same({ username = "expected a string" }, err)
    end)

    it("validates an integer", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "integer" } }
        }
      })
      assert.truthy(Test:validate({ f = 123 }))
      assert.truthy(Test:validate({ f = 0 }))
      assert.truthy(Test:validate({ f = -123 }))
      assert.falsy(Test:validate({ f = 0.5 }))
      assert.falsy(Test:validate({ f = -0.5 }))
      assert.falsy(Test:validate({ f = 1/0 }))
      assert.falsy(Test:validate({ f = -1/0 }))
      assert.falsy(Test:validate({ f = math.huge }))
      assert.falsy(Test:validate({ f = "123" }))
      assert.falsy(Test:validate({ f = "foo" }))
    end)

    it("validates a number", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "number" } }
        }
      })
      assert.truthy(Test:validate({ f = 123 }))
      assert.truthy(Test:validate({ f = 0 }))
      assert.truthy(Test:validate({ f = -123 }))
      assert.truthy(Test:validate({ f = 0.5 }))
      assert.truthy(Test:validate({ f = -0.5 }))
      assert.truthy(Test:validate({ f = 1/0 }))
      assert.truthy(Test:validate({ f = -1/0 }))
      assert.truthy(Test:validate({ f = math.huge }))
      assert.falsy(Test:validate({ f = "123" }))
      assert.falsy(Test:validate({ f = "foo" }))
    end)

    it("validates a boolean", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "boolean" } }
        }
      })
      assert.truthy(Test:validate({ f = true }))
      assert.truthy(Test:validate({ f = false }))
      assert.falsy(Test:validate({ f = 0 }))
      assert.falsy(Test:validate({ f = 1 }))
      assert.falsy(Test:validate({ f = "true" }))
      assert.falsy(Test:validate({ f = "false" }))
      assert.falsy(Test:validate({ f = "foo" }))
    end)

    it("fails on unknown fields", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "number", required = true } }
        }
      })
      assert.falsy(Test:validate({ f = 1, k = "wat" }))
    end)

    it("validates on unknown fields with value of null in data plane", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "number", required = true } }
        }
      })
      assert.falsy(Test:validate({ f = 1, k = "wat" }))
      assert.falsy(Test:validate({ f = 1, k = ngx.null }))

      _G.kong = {
        configuration = {
          role = "data_plane",
        },
      }

      local ok = Test:validate({ f = 1, k = ngx.null })

      _G.kong = nil
      assert.truthy(ok)
    end)

    local function run_custom_check_producing_error(error)
      local Test = Schema.new({
        fields = {
          { password = { type = "string" }, },
          { confirm_password = { type = "string" }, },
        }
      })
      local check = function(fields)
        if fields.password ~= fields.confirm_password then
          return nil, error
        end
        return true
      end

      Test.check = check
      local data, errs = Test:validate({
        password = "123456",
        confirm_password = "123456",
      })
      Test.check = nil
      assert.is_nil(errs)
      assert.truthy(data)

      Test.check = check
      local entity_errs
      data, errs, entity_errs = Test:validate({
        password = "123456",
        confirm_password = "1234",
      })
      Test.check = nil
      assert.falsy(data)
      return errs, entity_errs
    end

    it("runs a custom check with string error", function()
      local errors = run_custom_check_producing_error(
        "passwords must match"
      )
      assert.same({ ["@entity"] = { "passwords must match" } }, errors)
    end)

    it("runs a custom check with table keyed error", function()
      local errors = run_custom_check_producing_error(
        { password = "passwords must match" }
      )
      assert.same({ password = "passwords must match" }, errors)
    end)

    it("runs a custom check with table numbered error", function()
      local errors = run_custom_check_producing_error(
        { "passwords must match", "a second error" }
      )
      assert.same({
        ["@entity"] = {"passwords must match", "a second error" }
      }, errors)
    end)

    it("runs a custom check with no message", function()
      local errors = run_custom_check_producing_error(nil)
      -- still produces a default message
      assert.same({
        ["@entity"] = { "entity check failed" }
      }, errors)
    end)

    it("merges field and custom checks", function()
      local Test = Schema.new({
        fields = {
          { fail1 = { type = "string", match = "aaa" } },
          { fail2 = { type = "string", match = "bbb" } },
        },
        check = function()
          return nil, {
            [1] = "a generic check error",
            [2] = "another generic check error",
            fail2 = "my own field error",
          }
        end,
      })
      local data, errs = Test:validate({
        fail1 = "ccc",
        fail2 = "ddd",
      })
      assert.falsy(data)
      assert.same("a generic check error", errs["@entity"][1])
      assert.same("another generic check error", errs["@entity"][2])
      assert.string(errs["fail1"])
      assert.same("my own field error", errs["fail2"])
    end)

    it("can make a string from an error", function()
      local Test = Schema.new({
        fields = {
          { foo = { type = "typo" }, },
        }
      })
      local ret, errs = Test:validate({ foo = "foo" })
      assert.falsy(ret)
      assert.string(errs["foo"])

      local errmsg = Test:errors_to_string(errs)
      assert.string(errmsg)

      -- Produced string mentions the relevant error
      assert.match("foo", errmsg)
    end)

    it("produces no string when given no errors", function()
      local Test = Schema.new({
        fields = {}
      })
      local errmsg = Test:errors_to_string({})
      assert.falsy(errmsg)
      errmsg = Test:errors_to_string(nil)
      assert.falsy(errmsg)
      errmsg = Test:errors_to_string("not a table")
      assert.falsy(errmsg)
    end)

    describe("subschemas", function()
      it("validates loading a subschema", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { config = { type = "record", abstract = true, } },
          }
        })
        assert(Test:new_subschema("my_subschema", {
          fields = {
            { config = {
                type = "record",
                fields = {
                  { foo = { type = "string" } },
                  { bar = { type = "integer" } },
                }
            } }
          }
        }))
        assert.truthy(Test:validate({
          name = "my_subschema",
          config = {
            foo = "hello",
            bar = 123,
          }
        }))
      end)

      it("fails if subschema doesn't exist", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
          }
        })
        local ok, errors = Test:validate({
          name = "my_invalid_subschema",
        })
        assert.falsy(ok)
        assert.same({
          ["name"] = "unknown type: my_invalid_subschema",
        }, errors)
      end)

      it("fails if subschema doesn't exist", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "protocols",
          fields = {
            { protocols = { type = "array", elements = { type = "string", one_of = { "p1", "p2" }}, } },
          }
        })
        local ok, errors = Test:validate({
          protocols = { "p1" },
        })
        assert.falsy(ok)
        assert.same({
          ["protocols"] = "unknown type: p1",
        }, errors)

        local ok, errors = Test:validate({
          protocols = { "p2" },
        })
        assert.falsy(ok)
        assert.same({
          ["protocols"] = "unknown type: p2",
        }, errors)
      end)

      it("ignores missing non-required abstract fields", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { config = { type = "record", abstract = true, } },
            { bla = { type = "integer", abstract = true, } },
          }
        })
        assert(Test:new_subschema("my_subschema", {
          fields = {
            { config = {
                type = "record",
                fields = {
                  { foo = { type = "string" } },
                  { bar = { type = "integer" } },
                }
            } }
          }
        }))
        assert.truthy(Test:validate({
          name = "my_subschema",
          config = {
            foo = "hello",
            bar = 123,
          }
        }))
      end)

      it("cannot introduce new top-level fields", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { config = {
                type = "record",
                fields = {
                  { foo = { type = "integer" } },
                }
            } },
          }
        })
        local ok, err = Test:new_subschema("my_subschema", {
          fields = {
            { config = {
                type = "record",
                fields = {
                  { foo = { type = "integer" } },
                  { bar = { type = "integer" } },
                }
            } },
            { new_field = { type = "string", required = true, } },
          }
        })
        assert.falsy(ok)
        assert.matches("new_field: cannot create a new field", err, 1, true)
      end)

      it("fails when trying to use an abstract field (incomplete subschema)", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { config = { type = "record", abstract = true, } },
            { bla = { type = "integer", abstract = true, } },
          }
        })
        assert(Test:new_subschema("my_subschema", {
          fields = {
            { config = {
                type = "record",
                fields = {
                  { foo = { type = "string" } },
                  { bar = { type = "integer" } },
                }
            } }
          }
        }))
        local ok, errors = Test:validate({
          name = "my_subschema",
          config = {
            foo = "hello",
            bar = 123,
          },
          bla = 456,
        })
        assert.falsy(ok)
        assert.same({
          bla = "error in schema definition: abstract field was not specialized",
        }, errors)
      end)

      it("validates using both schema and subschema", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { bla = { type = "integer", } },
            { config = { type = "record", abstract = true, } },
          }
        })
        assert(Test:new_subschema("my_subschema", {
          fields = {
            { config = {
                type = "record",
                fields = {
                  { foo = { type = "string" } },
                  { bar = { type = "integer" } },
                }
            } }
          }
        }))
        local ok, errors = Test:validate({
          name = "my_subschema",
          bla = 4.5,
          config = {
            foo = 456,
            bar = 123,
          }
        })
        assert.falsy(ok)
        assert.same({
          bla = "expected an integer",
          config = {
            foo = "expected a string",
          }
        }, errors)
      end)

      it("can specialize a field of the parent schema", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { consumer = { type = "string", } },
          }
        })
        assert(Test:new_subschema("length_5", {
          fields = {
            { consumer = {
                type = "string",
                len_eq = 5,
            } }
          }
        }))
        assert(Test:new_subschema("no_restrictions", {
          fields = {}
        }))

        local ok, errors = Test:validate({
          name = "length_5",
          consumer = "aaa",
        })
        assert.falsy(ok)
        assert.same({
          consumer = "length must be 5",
        }, errors)

        ok = Test:validate({
          name = "length_5",
          consumer = "aaaaa",
        })
        assert.truthy(ok)

        ok = Test:validate({
          name = "no_restrictions",
          consumer = "aaa",
        })
        assert.truthy(ok)

      end)

      it("cannot change type when specializing a field", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { consumer = { type = "string", } },
          }
        })
        local ok, err = Test:new_subschema("length_5", {
          fields = {
            { consumer = {
                type = "integer",
            } }
          }
        })
        assert.falsy(ok)
        assert.matches("consumer: cannot change type in a specialized field", err, 1, true)
      end)

      it("a specialized field can force a value using 'eq'", function()
        assert(Schema.new({
          name = "mock_consumers",
          primary_key = { "id" },
          fields = {
            { id = { type = "string" }, },
          }
        }))

        local Test = assert(Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { consumer = { type = "foreign", reference = "mock_consumers" } },
          }
        }))
        assert(Test:new_subschema("no_consumer", {
          fields = {
            { consumer = { type = "foreign", reference = "mock_consumers", eq = ngx.null } }
          }
        }))
        assert(Test:new_subschema("no_restrictions", {
          fields = {}
        }))

        local ok, errors = Test:validate({
          name = "no_consumer",
          consumer = { id = "hello" },
        })
        assert.falsy(ok)
        assert.same({
          consumer = "value must be null",
        }, errors)

        ok = Test:validate({
          name = "no_consumer",
          consumer = ngx.null,
        })
        assert.truthy(ok)

        ok = Test:validate({
          name = "no_restrictions",
          consumer = { id = "hello" },
        })
        assert.truthy(ok)

      end)

    end)

    describe("entity_checkers", function()

      describe("conditional_at_least_one_of", function()
        local Test = Schema.new({
          fields = {
            { a = { type = "number" }, },
            { b = { type = "string" }, },
            { c = { type = "string" }, },
          },
          entity_checks = {
            { conditional_at_least_one_of = { if_field = "a",
                                              if_match = { gt = 0 },
                                              then_at_least_one_of = { "b", "c" }}
            },
          }
        })

        it("sanity", function()
          local ok, errs = Test:validate_insert({ a = 1 })
          assert.is_nil(ok)
          assert.same({
            "at least one of these fields must be non-empty: 'b', 'c'"
          }, errs["@entity"])

          local ok, errs = Test:validate_insert({ a = 1, b = "foo" })
          assert.is_nil(errs)
          assert.truthy(ok)
        end)

        it("does not run when condition is evaluated to false", function()
          local ok, errs = Test:validate_insert({ a = 0 })
          assert.is_nil(errs)
          assert.truthy(ok)
        end)

        it("does not run when the 'if_field' is missing", function()
          local ok, errs = Test:validate_insert({ b = "foo" })
          assert.is_nil(errs)
          assert.truthy(ok)
        end)

        it("works on updates", function()
          assert.truthy(Test:validate_insert({ }))

          -- Can update to whole valid record
          assert.truthy(Test:validate_update({ a = 123, b = "foo" }))

          -- Empty update works
          assert.truthy(Test:validate_update({ }))

          -- Cannot update if_field without respecifying at least one
          -- of the then_at_least_one_of fields, because this checker
          -- does not trigger a read-before-write (yet)
          local ok, err = Test:validate_update({ a = 123 })
          assert.falsy(ok)
          assert.same({
            ["@entity"] = {
              [[when updating, at least one of these fields must be non-empty: 'b', 'c']]
            }
          }, err)
        end)

        it("supports an 'else' clause", function()
          local Test = Schema.new({
            fields = {
              { a = { type = "number" }, },
              { b = { type = "string" }, },
              { c = { type = "string" }, },
              { d = { type = "string" }, },
            },
            entity_checks = {
              { conditional_at_least_one_of = { if_field = "a",
                                                if_match = { gt = 0 },
                                                then_at_least_one_of = { "b", "c" },
                                                else_match = { ne = 0 },
                                                else_then_at_least_one_of = { "c", "d" }, }
              },
            }
          })

          local ok, errs = Test:validate_insert({ a = -1 })
          assert.is_nil(ok)
          assert.same({
            "at least one of these fields must be non-empty: 'c', 'd'"
          }, errs["@entity"])

          local ok, errs = Test:validate_insert({ a = -1, d = "foo" })
          assert.is_nil(errs)
          assert.truthy(ok)

          local ok, errs = Test:validate_insert({ a = 0 })
          assert.is_nil(errs)
          assert.truthy(ok)
        end)

        it("supports a custom error message", function()
          local Test = Schema.new({
            fields = {
              { a = { type = "number" }, },
              { b = { type = "string" }, },
              { c = { type = "string" }, },
            },
            entity_checks = {
              { conditional_at_least_one_of = { if_field = "a",
                                                if_match = { gt = 0 },
                                                then_at_least_one_of = { "b", "c" },
                                                then_err = "must set one of %s if 'a' is like this",
                                                else_match = { ne = 0 },
                                                else_then_at_least_one_of = { "c", "d" },
                                                else_then_err = "must set one of %s if 'a' is like that" }, },
            }
          })

          local ok, errs = Test:validate_insert({ a = 1 })
          assert.falsy(ok)
          assert.same({
            "must set one of 'b', 'c' if 'a' is like this"
          }, errs["@entity"])

          local ok, errs = Test:validate_insert({ a = -1 })
          assert.falsy(ok)
          assert.same({
            "must set one of 'c', 'd' if 'a' is like that"
          }, errs["@entity"])
        end)
      end)

      describe("conditional", function()
        it("can check on false", function()
          local Test = Schema.new({
            fields = {
              { a = { type = "boolean" }, },
              { b = { type = "boolean" }, },
            },
            entity_checks = {
              { conditional = { if_field = "a",
                                if_match = { eq = true },
                                then_field = "b",
                                then_match = { eq = false },
                                then_err = "can't have a and b at the same time", }
              },
            }
          })

          assert.truthy(Test:validate_insert({ a = true, b = false }))
          local ok, errs = Test:validate_insert({ a = true, b = true })
          assert.falsy(ok)
          assert.same({
            "can't have a and b at the same time"
          }, errs["@entity"])
        end)

        it("supports a custom error message", function()
          local Test = Schema.new({
            fields = {
              { a = { type = "number" }, },
              { b = { type = "string" }, },
              { c = { type = "string" }, },
            },
            entity_checks = {
              { conditional = { if_field = "a",
                                if_match = { gt = 0 },
                                then_field = "b",
                                then_match = { gt = 0 },
                                then_err = "must set 'b > 0' if '%s' is like this", }
              },
            }
          })

          local ok, errs = Test:validate_insert({ a = 1, b = 0 })
          assert.falsy(ok)
          assert.same({
            "must set 'b > 0' if 'a' is like this"
          }, errs["@entity"])
        end)
      end)
    end)
  end)

  describe("validate_primary_key", function()

    it("validates primary keys", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "string"  }, },
          { b = { type = "number" }, },
          { c = { type = "number", default = 110 }, },
        }
      })
      Test.primary_key = { "a", "c" }
      assert.truthy(Test:validate_primary_key({
        a = "hello",
        c = 195
      }))
    end)

    it("fails on missing required primary keys", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "string"  }, },
          { b = { type = "number" }, },
          { c = { type = "number", required = true }, },
        }
      })
      Test.primary_key = { "a", "c" }
      local ok, errs = Test:validate_primary_key({
        a = "hello",
      })
      assert.falsy(ok)
      assert.truthy(errs["c"])
    end)

    it("fails on missing foreign primary keys", function()
      assert(Schema.new({
        name = "schema-test",
        primary_key = { "id" },
        fields = {
          { id = { type = "string" }, },
        }
      }))
      local Test = assert(Schema.new({
        name = "Test",
        fields = {
          { f = { type = "foreign", reference = "schema-test" } },
          { b = { type = "number" }, },
          { c = { type = "number" }, },
        }
      }))
      Test.primary_key = { "f" }
      local ok, errs = Test:validate_primary_key({})
      assert.falsy(ok)
      assert.match("missing primary key", errs["f"])
    end)

    it("fails on bad foreign primary keys", function()
      assert(Schema.new({
        name = "schema-test",
        primary_key = { "id" },
        fields = {
          { id = { type = "string", required = true }, },
        }
      }))
      local Test = assert(Schema.new({
        name = "Test",
        fields = {
          { f = { type = "foreign", reference = "schema-test" } },
          { b = { type = "number" }, },
          { c = { type = "number" }, },
        }
      }))
      Test.primary_key = { "f" }
      local ok, errs = Test:validate_primary_key({
        f = { id = ngx.null },
      })
      assert.falsy(ok)
      assert.match("required field missing", errs["f"].id)
    end)

    it("accepts a null in foreign if a null fails on bad foreign primary keys", function()
      package.loaded["kong.db.schema.entities.schema-test"] = {
        name = "schema-test",
        primary_key = { "id" },
        fields = {
          { id = { type = "string", required = true }, },
        }
      }
      local Test = assert(Schema.new({
        name = "Test",
        fields = {
          { f = { type = "foreign", reference = "schema-test" } },
          { b = { type = "number" }, },
          { c = { type = "number" }, },
        }
      }))
      Test.primary_key = { "f" }
      local ok, errs = Test:validate_primary_key({
        f = { id = ngx.null },
      })
      assert.falsy(ok)
      assert.match("required field missing", errs["f"].id)
    end)

    it("fails given non-primary keys", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "string"  }, },
          { b = { type = "number" }, },
          { c = { type = "number", required = true }, },
        }
      })
      Test.primary_key = { "a", "c" }
      local ok, errs = Test:validate_primary_key({
        a = "hello",
        b = 123,
        c = 9,
      })
      assert.falsy(ok)
      assert.truthy(errs["b"])
    end)

    it("fails given invalid keys", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "string"  }, },
          { b = { type = "number" }, },
          { c = { type = "number", required = true }, },
        }
      })
      Test.primary_key = { "a", "c" }
      local ok, errs = Test:validate_primary_key({
        a = "hello",
        x = 123,
      })
      assert.falsy(ok)
      assert.truthy(errs["x"])
    end)

    it("fails on missing non-required primary key", function()
      local Test = Schema.new({
        fields = {
          a = { type = "string"  },
          b = { type = "number" },
          c = { type = "number" },
        }
      })
      Test.primary_key = { "a", "c" }
      assert.falsy(Test:validate_primary_key({
        a = "hello",
      }))
    end)

  end)

  describe("validate_insert", function()

    it("demands required fields", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "number", required = true } }
        }
      })
      assert.truthy(Test:validate_insert({ f = 123 }))
      assert.falsy(Test:validate_insert({}))
    end)

  end)

  describe("validate_update", function()

    it("does not demand required fields", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "number", required = true } }
        }
      })
      assert.truthy(Test:validate_update({ f = 123 }))
      assert.truthy(Test:validate_update({}))
    end)

    it("demands interdependent fields", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "number" } },
          { b = { type = "number" } },
          { c = { type = "number" } },
          { d = { type = "number" } },
        },
        entity_checks = {
          { only_one_of = { "a", "b" } },
        }
      })
      assert.falsy(Test:validate_update({ a = 12 }))
      assert.falsy(Test:validate_update({ a = ngx.null, b = ngx.null }))
      assert.truthy(Test:validate_update({ a = 12, b = ngx.null }))
    end)

    it("test conditional checks", function()
      local Test = Schema.new({
        fields = {
          { policy = {
              type = "string",
              one_of = { "redis", "bla" },
              not_one_of = { "cluster" },
            }
          },
          { redis_host = { type = "string" } },
          { redis_port = { type = "number" } },
        },
        entity_checks = {
          { conditional = { if_field = "policy",
                            if_match = { match = "^redis$" },
                            then_field = "redis_host",
                            then_match = { required = true } } },
          { conditional = { if_field = "policy",
                            if_match = { match = "^redis$" },
                            then_field = "redis_port",
                            then_match = { required = true } } },
        }
      })
      local ok, err = Test:validate_update({ policy = "redis" })
      assert.falsy(ok)
      assert.truthy(err)
      assert.falsy(Test:validate_update({
        policy = "redis",
        redis_host = ngx.null,
        redis_port = ngx.null,
      }))
      assert.truthy(Test:validate_update({
        policy = "redis",
        redis_host = "example.com",
        redis_port = 80
      }))
      assert.truthy(Test:validate_update({
        policy = "bla",
      }))
      assert.falsy(Test:validate_update({
        policy = "redis",
      }))
      assert.falsy(Test:validate_update({
        policy = "cluster",
      }))
    end)

    it("test mutually required checks", function()
      local Test = Schema.new({
        fields = {
          { a1 = { type = "string" } },
          { a2 = { type = "string" } },
          { a3 = { type = "string" } },
        },
        entity_checks = {
          { mutually_required = { "a2" } },
          { mutually_required = { "a1", "a3" } },
        }
      })

      local ok, err = Test:validate_update({
        a1 = "foo"
      })
      assert.is_falsy(ok)
      assert.match("all or none of these fields must be set: 'a1', 'a3'", err["@entity"][1])

      ok, err = Test:validate_update({
        a2 = "foo"
      })
      assert.truthy(ok)
      assert.falsy(err)
    end)

    it("test mutually exclusive checks", function()
      local Test = Schema.new({
        fields = {
          { a1 = { type = "string" } },
          { a2 = { type = "string" } },
          { a3 = { type = "string" } },
        },
        entity_checks = {
          { mutually_exclusive = { "a2" } },
          { mutually_exclusive = { "a1", "a3" } },
        }
      })

      local ok, err = Test:validate_update({
        a1 = "foo",
        a3 = "foo",
      })
      assert.is_falsy(ok)
      assert.match("only one or none of these fields must be set: 'a1', 'a3'", err["@entity"][1])

      ok, err = Test:validate_update({
        a2 = "foo"
      })
      assert.truthy(ok)
      assert.falsy(err)

      ok, err = Test:validate_update({
        a1 = "foo",
        a2 = "foo",
      })
      assert.truthy(ok)
      assert.falsy(err)

      ok, err = Test:validate_update({})
      assert.truthy(ok)
      assert.falsy(err)
    end)

    for i = 1, 2 do
    it("test mutually required checks specified by transformations (" .. SchemaKind[i].name .. ")", function()
        local Test = SchemaKind[i].new({
          fields = {
            { name = { type = "string", required = true, } },
            { a1 = { type = "string" } },
            { a2 = { type = "string" } },
            { a3 = { type = "string" } },
          },
          transformations = {
            {
              input = { "a2" },
              on_write = function() return {} end
            },
            {
              input = { "a1", "a3" },
              on_write = function() return {} end
            },
          }
        })

        local ok, err = Test:validate_update({
          name = "test",
          a1 = "foo"
        })
        assert.is_falsy(ok)
        assert.match("all or none of these fields must be set: 'a1', 'a3'", err["@entity"][1])

        ok, err = Test:validate_update({
          a2 = "foo"
        })
        assert.truthy(ok)
        assert.falsy(err)

        ok, err = Test:validate_update({
          a1 = "aaa",
          a2 = "bbb",
          a3 = "ccc",
          a4 = "ddd",
        }, {
          a1 = "foo"
        })

        assert.is_falsy(ok)
        assert.match("all or none of these fields must be set: 'a1', 'a3'", err["@entity"][1])
    end)
    end

    for i = 1, 2 do
    it("test mutually required checks specified by transformations with needs (" .. SchemaKind[i].name .. ")", function()
      local Test = SchemaKind[i].new({
        fields = {
          { a1 = { type = "string" } },
          { a2 = { type = "string" } },
          { a3 = { type = "string" } },
          { a4 = { type = "string" } },
        },
        transformations = {
          {
            input = { "a2" },
            on_write = function() return {} end
          },
          {
            input = { "a1", "a3" },
            needs = { "a4" },
            on_write = function() return {} end
          },
        }
      })

      local ok, err = Test:validate_update({
        a1 = "foo"
      })
      assert.is_falsy(ok)
      assert.match("all or none of these fields must be set: 'a1', 'a3', 'a4'", err["@entity"][1])

      local ok, err = Test:validate_update(
        {
          a1 = "foo",
          a3 = "bar",
          a4 = "car",
        },
        {
          a1 = "foo",
          a3 = "bar",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      ok, err = Test:validate_update({
        a2 = "foo"
      })
      assert.truthy(ok)
      assert.falsy(err)
    end)
    end

    for i = 1, 2 do
    it("test mutually required checks specified by transformations with needs (combinations) (" .. SchemaKind[i].name .. ")", function()
      -- {
      --   input = I1, I2
      --   needs = N1, N2
      -- }
      --
      -- ### PATCH          result
      -- -----------------------------------------
      -- 01. (no input)     ok
      -- 02. I1 I2 N1 N2    ok
      -- 03. I1 I2 N1       ok, rbw N2
      -- 04. I1 I2    N2    ok, rbw N1
      -- 05. I1 I2          ok, rbw N1 N2
      -- 06. I1 I2          fail, rbw N1, missing N2
      -- 07. I1 I2          fail, rbw N2, missing N1
      -- 08. I1 I2          fail, missing N1 N2
      -- 09. I1    N1 N2    fail, missing I2
      -- 10. I1    N1       fail, missing I2
      -- 11. I1    N1       fail, missing I2, rbw N2
      -- 12. I1    N1       fail, rbw I2 N2
      -- 13. I1       N2    fail, missing I2
      -- 14. I1       N2    fail, missing I2, rbw N1
      -- 15. I1       N2    fail, rbw I2 N1
      -- 16. I1             fail, missing I2
      -- 17. I1             fail, missing I2, rbw N1
      -- 18. I1             fail, missing I2, rbw N1 N2
      -- 19. I1             fail, rbw I2 N1 N2
      -- 20. I2 N1 N2       fail, missing I1
      -- 21. I2 N1          fail, missing I1
      -- 22. I2    N2       fail, missing I1
      -- 23. I2             fail, missing I1
      -- 24. N1 N2          fail, needs changes would invalidate I1 I2
      -- 25. N1             fail, needs changes would invalidate I1 I2
      -- 26. N2             fail, needs changes would invalidate I1 I2
      -- 27. N1 N2          ok, no changes in needs, would not invalidate I1 I2
      -- 28. N1             ok, no changes in needs, would not invalidate I1 I2
      -- 29. N2             ok, no changes in needs, would not invalidate I1 I2

      local Test = SchemaKind[i].new({
        fields = {
          { i1 = { type = "string" } },
          { i2 = { type = "string" } },
          { n1 = { type = "string" } },
          { n2 = { type = "string" } },
        },
        transformations = {
          {
            input = { "i1", "i2" },
            needs = { "n1", "n2" },
            on_write = function() return {} end,
          },
        },
      })

      -- 01. (no input): ok
      local ok, err = Test:validate_update(
        {
        },
        {
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      -- 02. I1 I2 N1 N2: ok
      local ok, err = Test:validate_update(
        {
        },
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      -- 03. I1 I2 N1: ok, rbw N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      -- 04. I1 I2 N2: ok, rbw N1
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          i2 = "bar",
          n2 = "bar",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      -- 05. I1 I2 ok, rbw N1 N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          i2 = "bar",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      -- 06. I1 I2: fail, rbw N1, missing N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
        },
        {
          i1 = "foo",
          i2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 07. I1 I2: fail, rbw N2, missing N1
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n2 = "bar",
        },
        {
          i1 = "foo",
          i2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 08. I1 I2: fail, missing N1 N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n2 = "bar",
        },
        {
          i1 = "foo",
          i2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 09. I1 N1 N2: fail, missing I2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          n1 = "foo",
          n2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 10. I1 N1: fail, missing I2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          n1 = "foo",
        },
        {
          i1 = "foo",
          n1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 11. I1 N1: fail, missing I2, rbw N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          n1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 12. I1 N1: fail, rbw I2 N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          n1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2'", err["@entity"][1])

      -- 13. I1 N2: fail, missing I2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          n2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 14. I1 N2: fail, missing I2, rbw N1
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          n2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 15. I1 N2: fail, missing I2, rbw I2 N1
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
          n2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2'", err["@entity"][1])

      -- 16. I1: fail, missing I2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
        },
        {
          i1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 17. I1: fail, missing I2, rbw N1
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          n1 = "foo",
        },
        {
          i1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 18. I1: fail, missing I2, rbw N1 N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 19. I1: fail, rbw I2 N1 N2
      local ok, err = Test:validate_update(
        {
          i1 = "foo",
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2'", err["@entity"][1])

      -- 20. I2 N1 N2: fail, missing I1
      local ok, err = Test:validate_update(
        {
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        },
        {
          i2 = "bar",
          n1 = "foo",
          n2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 21. I2 N1: fail, missing I1
      local ok, err = Test:validate_update(
        {
          i2 = "bar",
          n1 = "foo",
        },
        {
          i2 = "bar",
          n1 = "foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 22. I2 N2: fail, missing I1
      local ok, err = Test:validate_update(
        {
          i2 = "bar",
          n2 = "bar",
        },
        {
          i2 = "bar",
          n2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 23. I2: fail, missing I1
      local ok, err = Test:validate_update(
        {
          i2 = "bar",
        },
        {
          i2 = "bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 24. N1 N2: fail, needs changes would invalidate I1 I2
      local ok, err = Test:validate_update(
        {
          n1 = "foo",
          n2 = "bar",
        },
        {
          n1 = "foo",
          n2 = "bar",
        },
        {
          n1 = "old-foo",
          n2 = "old-bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 25. N1: fail, needs changes would invalidate I1 I2
      local ok, err = Test:validate_update(
        {
          n1 = "foo",
        },
        {
          n1 = "foo",
        },
        {
          n1 = "old-foo",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 26. N2: fail, needs changes would invalidate I1 I2
      local ok, err = Test:validate_update(
        {
          n2 = "bar",
        },
        {
          n2 = "bar",
        },
        {
          n2 = "old-bar",
        }
      )
      assert.falsy(ok)
      assert.match("all or none of these fields must be set: 'i1', 'i2', 'n1', 'n2'", err["@entity"][1])

      -- 27. N1 N2: ok, no changes in needs, would not invalidate I1 I2
      local ok, err = Test:validate_update(
        {
          n1 = "foo",
          n2 = "bar",
        },
        {
          n1 = "foo",
          n2 = "bar",
        },
        {
          n1 = "foo",
          n2 = "bar",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      -- 28. N1: fail, ok, no changes in needs, would not invalidate I1 I2
      local ok, err = Test:validate_update(
        {
          n1 = "foo",
        },
        {
          n1 = "foo",
        },
        {
          n1 = "foo",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)

      -- 29. N2: ok, no changes in needs, would not invalidate I1 I2
      local ok, err = Test:validate_update(
        {
          n2 = "bar",
        },
        {
          n2 = "bar",
        },
        {
          n2 = "bar",
        }
      )
      assert.truthy(ok)
      assert.falsy(err)
    end)
    end

    it("test mutually exclusive checks", function()
      local Test = Schema.new({
        fields = {
          { a1 = { type = "string" } },
          { a2 = { type = "string" } },
          { a3 = { type = "string" } },
          { a4 = { type = "string" } },
          { a5 = { type = "string" } },
        },
        entity_checks = {
          { mutually_exclusive_sets = { set1 = {"a3"}, set2 = {"a5"}} },
          { mutually_exclusive_sets = { set1 = {"a1", "a2"}, set2 = {"a4", "a5"}} },
        }
      })

      local ok, err = Test:validate_update({
        a1 = "foo",
        a5 = "bla",
      })
      assert.is_falsy(ok)
      assert.same("these sets are mutually exclusive: ('a1'), ('a5')", err["@entity"][1])

      ok, err = Test:validate_update({
        a1 = "foo",
      })
      assert.truthy(ok)
      assert.falsy(err)

      ok, err = Test:validate_update({
        a3 = "foo",
        a5 = "bla",
      })
      assert.is_falsy(ok)
      assert.same("these sets are mutually exclusive: ('a3'), ('a5')", err["@entity"][1])

      ok, err = Test:validate_update({
        a5 = "foo",
      })
      assert.truthy(ok)
      assert.falsy(err)
    end)

    it("test conditional checks on set elements", function()
      local Test = Schema.new({
        fields = {
          { redis_host = { type = "string" } },
          { a_set = { type = "set", elements = { type = "string", one_of = { "foo", "bar" }, not_one_of = { "forbidden", "also_forbidden" } } } },
        },
        entity_checks = {
          { conditional = { if_field = "a_set",
                            if_match = { elements = { type = "string", one_of = { "foo" } } },
                            then_field = "redis_host",
                            then_match = { eq = "host_foo" } } },
        }
      })
      local ok, err = Test:validate_update({
        a_set = { "foo" },
        redis_host = "host_foo",
      })
      assert.truthy(ok)
      assert.is_nil(err)

      ok, err = Test:validate_update({
        a_set = { "foo" },
        redis_host = "host_bar",
      })
      assert.falsy(ok)
      assert.same("value must be host_foo", err.redis_host)

      ok, err = Test:validate_update({
        a_set = { "bar" },
        redis_host = "any_other_host",
      })
      assert.truthy(ok)
      assert.is_nil(err)

      ok, err = Test:validate_update({
        a_set = { "forbidden" },
        redis_host = "host_foo",
      })
      assert.falsy(ok)
      assert.same("must not be one of: forbidden, also_forbidden", err.a_set[1])
    end)

    it("test custom entity checks", function()
      local Test = Schema.new({
        fields = {
          { aaa = { type = "string" } },
          { bbb = { type = "string" } },
          { ccc = { type = "number" } },
        },
        entity_checks = {
          { custom_entity_check = {
            field_sources = { "bbb", "ccc" },
            fn = function(entity)
              assert(entity.aaa == nil)
              if entity.bbb == "foo" and entity.ccc == 42 then
                return true
              end
              return nil, "oh no"
            end,
          } }
        }
      })
      local ok, err = Test:validate_update({
        aaa = "bar",
        bbb = "foo",
        ccc = 42
      })
      assert.truthy(ok)
      assert.falsy(err)

      ok, err = Test:validate_update({
        aaa = ngx.null,
        bbb = "foo",
        ccc = 42
      })
      assert.truthy(ok)
      assert.falsy(err)

      ok, err = Test:validate({
        aaa = ngx.null,
        bbb = "foo",
      })
      assert.falsy(ok)
      assert.match("field required for entity check", err["ccc"])

      ok, err = Test:validate_update({
        aaa = ngx.null,
        bbb = "foo",
      })
      assert.falsy(ok)
      assert.match("field required for entity check when updating", err["ccc"])

      ok, err = Test:validate_update({
        aaa = ngx.null,
      })
      assert.truthy(ok)
      assert.falsy(err)

      ok, err = Test:validate_update({
        bbb = "foo",
        ccc = 43
      })
      assert.falsy(ok)
      assert.match("oh no", err["@entity"][1])

      ok, err = Test:validate_update({
        bbb = "foooo",
        ccc = 42
      })
      assert.falsy(ok)
      assert.match("oh no", err["@entity"][1])
    end)

    it("does not run an entity check if fields have errors", function()
      local Test = Schema.new({
        fields = {
          { aaa = { type = "string" } },
          { bbb = { type = "string", len_min = 8 } },
          { ccc = { type = "number", between = { 0, 10 } } },
        },
        entity_checks = {
          { custom_entity_check = {
            field_sources = { "bbb", "ccc" },
            fn = function(entity)
              assert(entity.aaa == nil)
              if entity.bbb == "12345678" and entity.ccc == 2 then
                return true
              end
              return nil, "oh no"
            end,
          } }
        }
      })
      local ok, err = Test:validate_update({
        aaa = "bar",
        bbb = "foo",
        ccc = 42
      })
      assert.falsy(ok)
      assert.match("length must be at least 8", err["bbb"])
      assert.match("value should be between 0 and 10", err["ccc"])
      assert.falsy(err["@entity"])

      ok, err = Test:validate({
        aaa = ngx.null,
        bbb = "foo",
        ccc = 42
      })
      assert.falsy(ok)
      assert.match("length must be at least 8", err["bbb"])
      assert.match("value should be between 0 and 10", err["ccc"])
      assert.falsy(err["@entity"])

      ok, err = Test:validate({
        bbb = "AAAAAAAA",
        ccc = 9,
      })
      assert.falsy(ok)
      assert.match("oh no", err["@entity"][1])

      ok, err = Test:validate({
        bbb = "12345678",
        ccc = 2,
      })
      assert.truthy(ok)
      assert.falsy(err)
    end)

    it("run an entity check with flag 'run_with_missing_fields'", function()
      local Test = Schema.new({
        fields = {
          { aaa = { type = "string", len_min = 4 } },
          { bbb = { type = "string", len_min = 8 } },
          { ccc = { type = "number", between = { 0, 10 } } },
        },
        entity_checks = {
          { custom_entity_check = {
            run_with_missing_fields = true,
            field_sources = { "aaa", "bbb", "ccc" },
            fn = function(entity)
              if entity.aaa and entity.aaa ~= "abcd" then
                return nil, "oh no"
              end

              if entity.bbb == "12345678" and entity.ccc == 2 then
                return true
              end
              return nil, "oh no"
            end,
          } }
        }
      })

      -- missing field 'aaa'
      local ok, err = Test:validate_update({
        bbb = "foo",
        ccc = 42
      })
      assert.falsy(ok)
      assert.is_nil(err["aaa"])
      assert.match("length must be at least 8", err["bbb"])
      assert.match("value should be between 0 and 10", err["ccc"])
      assert.falsy(err["@entity"])

      -- has field 'aaa'
      local ok, err = Test:validate_update({
        aaa = "xxx",
        bbb = "foo",
        ccc = 42
      })
      assert.falsy(ok)
      assert.match("length must be at least 4", err["aaa"])
      assert.match("length must be at least 8", err["bbb"])
      assert.match("value should be between 0 and 10", err["ccc"])
      assert.falsy(err["@entity"])

      -- field 'aaa' has wrong value
      local ok, err = Test:validate_update({
        aaa = "xxxxxxxx",
        bbb = "12345678",
        ccc = 2
      })
      assert.falsy(ok)
      assert.truthy(err["@entity"])
      assert.match("oh no", err["@entity"][1])

      -- missing field 'aaa', others are right
      local ok, err = Test:validate_update({
        bbb = "12345678",
        ccc = 2
      })
      assert.truthy(ok)
      assert.falsy(err)

      -- all fields are right
      local ok, err = Test:validate_update({
        aaa = "abcd",
        bbb = "12345678",
        ccc = 2
      })
      assert.truthy(ok)
      assert.falsy(err)
    end)

    it("supports entity checks on nested fields", function()
      local Test = Schema.new({
        fields = {
          { config = {
              type = "record",
              fields = {
                { policy = { type = "string", one_of = { "redis", "bla" } } },
                { redis_host = { type = "string" } },
                { redis_port = { type = "number" } },
              }
          } }
        },
        entity_checks = {
          { conditional = { if_field = "config.policy",
                            if_match = { eq = "redis" },
                            then_field = "config.redis_host",
                            then_match = { required = true } } },
          { conditional = { if_field = "config.policy",
                            if_match = { eq = "redis" },
                            then_field = "config.redis_port",
                            then_match = { required = true } } },
        }
      })
      local ok, err = Test:validate_update({ config = { policy = "redis" } })
      assert.falsy(ok)
      assert.truthy(err)
      assert.falsy(Test:validate_update({
        config = {
          policy = "redis",
          redis_host = ngx.null,
          redis_port = ngx.null,
        }
      }))
      assert.truthy(Test:validate_update({
        config = {
          policy = "redis",
          redis_host = "example.com",
          redis_port = 80
        }
      }))
      assert.falsy(Test:validate_update({
        config = {
          policy = "redis",
        }
      }))
      assert.truthy(Test:validate_update({
        config = {
          policy = "bla",
        }
      }))
    end)

    it("does not demand interdependent fields that aren't being updated", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "number" } },
          { b = { type = "number" } },
          { c = { type = "number" } },
          { d = { type = "number" } },
        },
        entity_checks = {
          { only_one_of = { "a", "b" } },
        }
      })
      assert.truthy(Test:validate_update({ c = 15 }))
    end)

  end)

  describe("process_auto_fields", function()
    for _, context in ipairs({ "insert", "update", "upsert"}) do
      it('returns new table when called with "' .. context .. '" context', function()
        local Test = Schema.new({
          fields = {
            { f = { type = "string", default = "test" } },
          }
        })

        local original = {}
        local data, err = Test:process_auto_fields(original, context)
        assert.is_nil(err)
        assert.not_equal(original, data)
        if context == "update" then
          assert.is_nil(data.f)
        else
          assert.equal("test", data.f)
        end
        assert.is_nil(original.f)
      end)
    end

    it('modifies table in place when called with "select" context', function()
      local Test = Schema.new({
        fields = {
          { f = { type = "string", default = "test" } },
        }
      })

      local original = {}
      local data, err = Test:process_auto_fields(original, "select")
      assert.is_nil(err)
      assert.equal(original, data)
      assert.equal("test", data.f)
      assert.equal("test", original.f)
    end)

    it("produces ngx.null for non-required fields", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "array", elements = { type = "string" } }, },
          { b = { type = "set", elements = { type = "string" } }, },
          { c = { type = "number" }, },
          { d = { type = "integer" }, },
          { e = { type = "boolean" }, },
          { f = { type = "string" }, },
          { g = { type = "record", fields = {} }, },
          { h = { type = "map", keys = {}, values = {} }, },
          { i = { type = "function" }, },
          { j = { type = "json", json_schema = { inline = { type = "string" }, } }, },
        }
      })
      check_all_types_covered(Test.fields)
      local data, err = Test:process_auto_fields({})
      assert.is_nil(err)
      assert.same(ngx.null, data.a)
      assert.same(ngx.null, data.b)
      assert.same(ngx.null, data.c)
      assert.same(ngx.null, data.d)
      assert.same(ngx.null, data.e)
      assert.same(ngx.null, data.f)
      assert.same(ngx.null, data.g)
      assert.same(ngx.null, data.h)
      assert.same(ngx.null, data.i)
      assert.same(ngx.null, data.j)
    end)

    it("produces nil for empty string fields with selects", function()
      local Test = Schema.new({
        fields = {
          { str = { type = "string" }, },
          { rec = { type = "record", fields = { {
            str = { type = "string" }, }, {
            arr = { type = "array", elements = { type = "string" } }, }, {
            set = { type = "set", elements = { type = "string" } }, }, {
            map = { type = "map", keys = { type = "string" }, values = { type = "string" } }, }, {
            est = { type = "string", len_min = 0 }, }, }, }, },
          { arr = { type = "array", elements = { type = "string" } }, },
          { set = { type = "set", elements = { type = "string" } }, },
          { map = { type = "map", keys = { type = "string" }, values = { type = "string" } }, },
          { est = { type = "string", len_min = 0 }, },
        }
      })
      local data, err = Test:process_auto_fields({
        str = "",
        rec = {
          str = "",
          arr = { "", "a", "" },
          set = { "", "a", "" },
          map = { key = "" },
          est = "",
        },
        arr = { "", "a", "" },
        set = { "", "a", "" },
        map = { key = "" },
        est = "",
      }, "select")

      assert.is_nil(err)
      assert.equal(nil, data.str)              -- string
      assert.same({"", "a", ""}, data.arr)     -- array, TODO: should we remove empty strings from arrays?
      assert.same({"", "a" }, data.set)        -- set,   TODO: should we remove empty strings from sets?
      assert.same({ key = "" }, data.map)      -- map,   TODO: should we remove empty strings from maps?
      assert.equal("", data.est)

      -- record
      assert.equal(nil, data.rec.str)          -- string
      assert.same({"", "a", ""}, data.rec.arr) -- array, TODO: should we remove empty strings from arrays?
      assert.same({"", "a" }, data.rec.set)    -- set,   TODO: should we remove empty strings from sets?
      assert.same({ key = "" }, data.rec.map)  -- map,   TODO: should we remove empty strings from maps?
      assert.equal("", data.rec.est)
    end)

    it("produces ngx.null (when asked) for empty string fields with selects", function()
      local Test = Schema.new({
        fields = {
          { str = { type = "string" }, },
          { rec = { type = "record", fields = { {
            str = { type = "string" }, }, {
            arr = { type = "array", elements = { type = "string" } }, }, {
            set = { type = "set", elements = { type = "string" } }, }, {
            map = { type = "map", keys = { type = "string" }, values = { type = "string" } }, }, {
            est = { type = "string", len_min = 0 }, }, }, }, },
          { arr = { type = "array", elements = { type = "string" } }, },
          { set = { type = "set", elements = { type = "string" } }, },
          { map = { type = "map", keys = { type = "string" }, values = { type = "string" } }, },
          { est = { type = "string", len_min = 0 }, },
        }
      })
      local data, err = Test:process_auto_fields({
        str = "",
        rec = {
          str = "",
          arr = { "", "a", "" },
          set = { "", "a", "" },
          map = { key = "" },
          est = "",
        },
        arr = { "", "a", "" },
        set = { "", "a", "" },
        map = { key = "" },
        est = "",
      }, "select", true)
      assert.is_nil(err)
      assert.equal(cjson.null, data.str)       -- string
      assert.same({"", "a", ""}, data.arr)     -- array, TODO: should we set null empty strings from arrays?
      assert.same({"", "a" }, data.set)        -- set,   TODO: should we set null empty strings from sets?
      assert.same({ key = "" }, data.map)      -- map,   TODO: should we set null empty strings from maps?
      assert.equal("", data.est)

      -- record
      assert.equal(cjson.null, data.rec.str)   -- string
      assert.same({"", "a", ""}, data.rec.arr) -- array, TODO: should we set null empty strings from arrays?
      assert.same({"", "a" }, data.rec.set)    -- set,   TODO: should we set null empty strings from sets?
      assert.same({ key = "" }, data.rec.map)  -- map,   TODO: should we set null empty strings from maps?
      assert.equal("", data.rec.est)
    end)

    it("does not produce non-required fields on 'update'", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "array", elements = { type = "string" } }, },
          { b = { type = "set", elements = { type = "string" } }, },
          { c = { type = "number" }, },
          { d = { type = "integer" }, },
          { e = { type = "boolean" }, },
          { f = { type = "string" }, },
          { g = { type = "record", fields = {} }, },
          { h = { type = "map", keys = {}, values = {} }, },
          { i = { type = "function" }, },
          { j = { type = "json", json_schema = { inline = { type = "string" }, } }, },
        }
      })
      check_all_types_covered(Test.fields)
      local data, err = Test:process_auto_fields({}, "update")
      assert.is_nil(err)
      assert.is_nil(data.a)
      assert.is_nil(data.b)
      assert.is_nil(data.c)
      assert.is_nil(data.d)
      assert.is_nil(data.e)
      assert.is_nil(data.f)
      assert.is_nil(data.g)
      assert.is_nil(data.h)
      assert.is_nil(data.i)
    end)

    -- regression test for #3910
    it("lets invalid values pass unchanged", function()
      local Test = Schema.new({
        fields = {
          { my_array = { type = "array", elements = { type = "string" } }, },
          { my_set = { type = "set", elements = { type = "string" } }, },
          { my_number = { type = "number" }, },
          { my_integer = { type = "integer" }, },
          { my_boolean = { type = "boolean" }, },
          { my_string = { type = "string" }, },
          { my_record = { type = "record", fields = { { my_field = { type = "integer" } } } } },
          { my_map = { type = "map", keys = {}, values = {} }, },
          { my_function = { type = "function" }, },
          { my_json = { type = "json", json_schema = { inline = { type = "string" }, } }, },
        }
      })
      check_all_types_covered(Test.fields)
      local bad_value = {
        my_array = "hello",
        my_set = "hello",
        my_number = "hello",
        my_integer = "hello",
        my_boolean = "hello",
        my_string = 123,
        my_record = "hello",
        my_map = "hello",
        my_function = "hello",
        my_json = 123,
      }
      local data, err = Test:process_auto_fields(bad_value)
      assert.is_nil(err)
      assert.same(data, bad_value)

      local data2, err = Test:process_auto_fields(bad_value, "update")
      assert.is_nil(err)
      assert.same(data2, bad_value)
    end)

    it("honors given default values", function()
      local f = function() end

      local Test = Schema.new({
        fields = {
          { a = { type = "array",
                  elements = { type = "string" },
                  default = { "foo", "bar" } }, },
          { b = { type = "set",
                  elements = { type = "number" },
                  default = { 2112, 5150 } }, },
          { c = { type = "number", default = 1984 }, },
          { d = { type = "integer", default = 42 }, },
          { e = { type = "boolean", default = true }, },
          { f = { type = "string", default = "foo" }, },
          { g = { type = "map",
                  keys = { type = "string" },
                  values = { type = "number" },
                  default = { foo = 1, bar = 2 } }, },
          { h = { type = "record",
                        fields = {
                    { f = { type = "number" }, },
                  },
                  default = { f = 123 } }, },
          { i = { type = "function", default = f } },
          { nested_record = {
              type = "record",
              default = {
                r = {
                  a = "nr",
                  b = 123,
                }
              },
              fields = {
                { r = {
                    type = "record",
                    fields = {
                      { a = { type = "string" } },
                      { b = { type = "number" } }
                    }
                } }
              }
          } },
          { j = {
              type = "json",
              json_schema = { inline = { type = "string" }, },
          } },
        }
      })
      check_all_types_covered(Test.fields)
      local data = Test:process_auto_fields({})
      assert.same({ "foo", "bar" },     data.a)
      assert.same({ 2112, 5150 },       data.b)
      assert.same(1984,                 data.c)
      assert.same(42,                   data.d)
      assert.is_true(data.e)
      assert.same("foo",                data.f)
      assert.same({ foo = 1, bar = 2 }, data.g)
      assert.same({ f = 123 },          data.h)
      assert.same(f,                    data.i)
      assert.same({ r = { a = "nr", b = 123, }}, data.nested_record)
    end)

    it("detects an empty Lua table as a default for an set and marks it as a json array", function()
      local Test = Schema.new({
        fields = {
          { s = { type = "set",
                  elements = { type = "string" },
                  default = {} }, },
        }
      })
      local data = Test:process_auto_fields({})
      assert.equals('{"s":[]}', cjson.encode(data))
    end)


    it("detects an empty Lua table as a default for an array and marks it as a json array", function()
      local Test = Schema.new({
        fields = {
          { a = { type = "array",
                  elements = { type = "string" },
                  default = {} }, },
        }
      })
      local data = Test:process_auto_fields({})
      assert.equals('{"a":[]}', cjson.encode(data))
    end)

    it("accepts cjson.empty_array as a default for an array", function()
      local Test = Schema.new({
        fields = {
          { b = { type = "array",
                  elements = { type = "string" },
                  default = cjson.empty_array }, },
        }
      })
      local data = Test:process_auto_fields({})
      assert.equals('{"b":[]}', cjson.encode(data))
    end)

    it("accepts a table marked with cjson.empty_array_mt as a default for an array", function()
      local Test = Schema.new({
        fields = {
          { c = { type = "array",
                  elements = { type = "string" },
                  default = setmetatable({}, cjson.empty_array_mt) }, },
        }
      })
      local data = Test:process_auto_fields({})
      assert.equals('{"c":[]}', cjson.encode(data))
    end)

    it("accepts a table marked with cjson.array_mt as a default for an array", function()
      local Test = Schema.new({
        fields = {
          { d = { type = "array",
                  elements = { type = "string" },
                  default = setmetatable({}, cjson.array_mt) }, },
        }
      })
      local data = Test:process_auto_fields({})
      assert.equals('{"d":[]}', cjson.encode(data))
    end)

    it("nested defaults in required records produce a default record", function()
      local Test = Schema.new({
        fields = {
          { nested_record = {
              type = "record",
              required = true,
              fields = {
                { r = {
                    type = "record",
                    required = true,
                    fields = {
                      { a = { type = "string", default = "nr", } },
                      { b = { type = "number", default = 123, } }
                    }
                } }
              }
          } }
        }
      })
      local data = Test:process_auto_fields({})
      assert.same({ r = { a = "nr", b = 123, }}, data.nested_record)
    end)

    it("null in required records only produces a default record on select", function()
      local Test = Schema.new({
        fields = {
          { nested_record = {
              type = "record",
              required = true,
              fields = {
                { r = {
                    type = "record",
                    required = true,
                    fields = {
                      { a = { type = "string", default = "nr", } },
                      { b = { type = "number", default = 123, } }
                    }
                } }
              }
          } }
        }
      })
      local data = Test:process_auto_fields({ nested_record = ngx.null }, "insert")
      assert.same(ngx.null, data.nested_record)
      assert.falsy(Test:validate(data))

      data = Test:process_auto_fields({ nested_record = ngx.null }, "update")
      assert.same(ngx.null, data.nested_record)
      assert.falsy(Test:validate_update(data))

      data = Test:process_auto_fields({ nested_record = ngx.null }, "upsert")
      assert.same(ngx.null, data.nested_record)
      assert.falsy(Test:validate_update(data))

      data = Test:process_auto_fields({ nested_record = ngx.null }, "select")
      assert.same({ r = { a = "nr", b = 123, }}, data.nested_record)
      assert.truthy(Test:validate(data))
    end)

    it("honors 'false' as a default", function()
      local Test = Schema.new({
        fields = {
          { b = { type = "boolean", default = false }, },
        }
      })
      local t1 = Test:process_auto_fields({})
      assert.is_false(t1.b)
      local t2 = Test:process_auto_fields({ b = false })
      assert.is_false(t2.b)
      local t3 = Test:process_auto_fields({ b = true })
      assert.is_true(t3.b)
    end)

    it("honors 'true' as a default", function()
      local Test = Schema.new({
        fields = {
          { b = { type = "boolean", default = true }, },
        }
      })
      local t1 = Test:process_auto_fields({})
      assert.is_true(t1.b)
      local t2 = Test:process_auto_fields({ b = false })
      assert.is_false(t2.b)
      local t3 = Test:process_auto_fields({ b = true })
      assert.is_true(t3.b)
    end)

    it("does not demand required fields", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "number", required = true } }
        }
      })
      assert.truthy(Test:process_auto_fields({ f = 123 }))
      assert.truthy(Test:process_auto_fields({}))
    end)

    it("removes duplicates preserving order", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "set", elements = { type = "string" } } }
        }
      })
      local tests = {
        { {}, {} },
        { {"foo"}, {"foo"} },
        { {"foo", "bar"}, {"foo", "bar"} },
        { {"bar", "foo"}, {"bar", "foo"} },
        { {"foo", "foo", "bar"}, {"foo", "bar"} },
        { {"foo", "bar", "foo"}, {"foo", "bar"} },
        { {"foo", "foo", "foo"}, {"foo"} },
        { {"bar", "foo", "foo"}, {"bar", "foo"} },
      }
      for _, test in ipairs(tests) do
        assert.same({ f = test[2] }, Test:process_auto_fields({ f = test[1] }))
      end
    end)

    -- TODO is this behavior correct?
    it("non-required fields do not generate defaults", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "number" }, },
        }
      })
      local data = Test:process_auto_fields({})
      assert.same(ngx.null, data.f)
    end)

    it("auto-produces an UUID with 'uuid' and 'auto'", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "string", uuid = true, auto = true } }
        }
      })
      local tbl = {}
      tbl = Test:process_auto_fields(tbl, "insert")
      assert.match(uuid_pattern, tbl.f)
    end)

    it("auto-produces a random with 'string' and 'auto'", function()
      local Test = Schema.new({
        fields = {
          { f = { type = "string", auto = true } }
        }
      })
      local tbl = {}
      tbl = Test:process_auto_fields(tbl, "insert")
      assert.is_string(tbl.f)
      assert.equals(32, #tbl.f)
    end)

    it("auto-produces a timestamp with 'created_at' and 'auto'", function()
      local Test = Schema.new({
        fields = {
          { created_at = { type = "number", timestamp = true, auto = true } }
        }
      })
      local tbl = {}
      -- Does not insert `created_at` on "update"
      tbl = Test:process_auto_fields(tbl, "update")
      assert.falsy(tbl.created_at)
      -- It does insert it on "insert"
      tbl = Test:process_auto_fields(tbl, "insert")
      assert.number(tbl.created_at)
    end)

    it("auto-updates a timestamp with 'updated_at' and 'auto'", function()
      local Test = Schema.new({
        fields = {
          { updated_at = { type = "number", timestamp = true, auto = true } }
        }
      })
      local tbl = {}
      tbl = Test:process_auto_fields(tbl, "update")
      assert.number(tbl.updated_at)
      -- force updated_at downwards...
      local ts = tbl.updated_at - 10
      tbl.updated_at = ts
      -- ...and updates it again
      tbl = Test:process_auto_fields(tbl, "update")
      assert.number(tbl.updated_at)
      -- Note: this assumes the clock only moves forwards during the execution
      -- of the test. As we store UTC timestamps, we're immune to DST
      -- downward adjustments, and ntp leap second adjustments only move
      -- forward.
      assert.truthy(tbl.updated_at > ts)
    end)

    it("does not auto-update a timestamp with 'created_at' or 'updated_at' and 'auto' upon retrival", function()
      local Test = Schema.new({
        fields = {
          { created_at = { type = "number", timestamp = true, auto = true } },
          { updated_at = { type = "number", timestamp = true, auto = true } },
        }
      })
      local tbl = {}
      tbl = Test:process_auto_fields(tbl, "insert")
      assert.number(tbl.created_at)
      assert.number(tbl.updated_at)
      -- force updated_at downwards...
      local created_ts = tbl.created_at - 10
      local updated_ts = tbl.updated_at - 10
      tbl.created_at = created_ts
      tbl.updated_at = updated_ts
      -- ...and doesn't updates it again
      tbl = Test:process_auto_fields(tbl, "select")
      assert.number(tbl.created_at)
      assert.same(updated_ts, tbl.created_at)
      assert.number(tbl.updated_at)
      assert.same(updated_ts, tbl.updated_at)
    end)

    it("strips down the decimal part on integers when selecting, but not in other contexts", function()
      local Test = Schema.new({
        fields = {
          { fingers = { type = "integer" } }
        }
      })

      local tbl = Test:process_auto_fields({ fingers = 5.5 }, "select")
      assert.equals(5, tbl.fingers)

      local tbl = Test:process_auto_fields({ fingers = 5.5 }, "insert")
      assert.equals(5.5, tbl.fingers)
    end)

    it("adds cjson.array_mt on non-empty array fields", function()
      local Test = Schema.new({
        fields = {
          { arr = { type = "array", elements = { type = "string" } } },
        },
      })

      local tbl = Test:process_auto_fields({
        arr = { "hello" },
      }, "insert")

      assert.same(cjson.array_mt, getmetatable(tbl.arr))
    end)

    it("adds cjson.array_mt on empty array and set fields", function()
      local Test = Schema.new({
        fields = {
          { arr = { type = "array", elements = { type = "string" } } },
          { set = { type = "set",   elements = { type = "string" } } },
        },
      })

      local tbl = Test:process_auto_fields({
        arr = {},
        set = {}
      }, "insert")

      assert.same(cjson.array_mt, getmetatable(tbl.arr))
      assert.same(cjson.array_mt, getmetatable(tbl.set))
    end)

    it("adds cjson.array_mt on empty array and set fields", function()
      local Test = Schema.new({
        fields = {
          { arr = { type = "array", elements = { type = "string" } } },
          { set = { type = "set",   elements = { type = "string" } } },
        },
      })

      for _, operation in pairs{ "insert", "update", "select", "delete" } do
        local tbl = Test:process_auto_fields({
          arr = {},
          set = {}
        }, operation)

        assert.same(cjson.array_mt, getmetatable(tbl.arr))
        assert.same(cjson.array_mt, getmetatable(tbl.set))
      end
    end)

    it("adds a helper metatable to sets", function()
      local Test = Schema.new({
        fields = {
          { set = { type = "set", elements = { type = "string" } } },
        },
      })

      for _, operation in pairs{ "insert", "update", "select", "delete" } do
        local tbl = Test:process_auto_fields({
          set = { "http", "https" },
        }, operation)


        assert.equal("table", type(getmetatable(tbl.set)))

        assert.truthy(tbl.set.http)
        assert.truthy(tbl.set.https)
        assert.falsy(tbl.set.smtp)
      end
    end)

    it("does not add a helper metatable to maps", function()
      local Test = Schema.new({
        fields = {
          { map = { type = "map", keys = { type = "string" }, values = { type = "boolean" } } },
        },
      })

      for _, operation in pairs{ "insert", "update", "select", "delete" } do
        local tbl = Test:process_auto_fields({
          map = { http = true },
        }, operation)

        assert.is_nil(getmetatable(tbl.map))
        assert.is_true(tbl.map.http)
        assert.is_nil(tbl.map.https)
      end
    end)

    it("does add array_mt metatable to arrays", function()
      local Test = Schema.new({
        fields = {
          { arr = { type = "array", elements = { type = "string" } } },
        },
      })

      for _, operation in pairs{ "insert", "update", "select", "delete" } do
        local tbl = Test:process_auto_fields({
          arr = { "http", "https" },
        }, operation)

        assert.is_equal(cjson.array_mt, getmetatable(tbl.arr))
        assert.is_equal("http", tbl.arr[1])
        assert.is_nil(tbl.arr.http)
      end
    end)

    it("correctly flags check_immutable_fields when immutable present in schema", function()
      local test_schema = {
        name = "test",

        fields = {
          { name = { type = "string",  immutable = true }, },
        },
      }
      local test_entity = { name = "bob" }

      local TestEntities = Schema.new(test_schema)
      local _, _, check_immutable_fields =
        TestEntities:process_auto_fields(test_entity, "update")

      assert.truthy(check_immutable_fields)
    end)

    it("correctly flags check_immutable_fields when immutable absent from schema", function()
      local test_schema = {
        name = "test",

        fields = {
          { name = { type = "string" }, },
        },
      }
      local test_entity = { name = "bob" }

      local TestEntities = Schema.new(test_schema)
      local _, _, check_immutable_fields =
        TestEntities:process_auto_fields(test_entity, "update")

      assert.falsy(check_immutable_fields)
    end)

    describe("in subschemas", function()
      it("a specialized field can set a default", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { config = { type = "record", abstract = true } },
          }
        })
        assert(Test:new_subschema("my_subschema", {
          fields = {
            { config = {
                type = "record",
                fields = {
                  { foo = { type = "string", default = "bar" } },
                },
                default = { foo = "bla" }
             } }
          }
        }))

        local input = {
          name = "my_subschema",
          config = { foo = "hello" },
        }
        local ok = Test:validate(input)
        assert.truthy(ok)
        local output = Test:process_auto_fields(input)
        assert.same(input, output)

        input = {
          name = "my_subschema",
          config = nil,
        }
        ok = Test:validate(input)
        assert.truthy(ok)
        output = Test:process_auto_fields(input)
        assert.same({
          name = "my_subschema",
          config = {
            foo = "bla",
          }
        }, output)
      end)

      it("removes fields that have been removed from the schema (on select context)", function()
        local Test = Schema.new({
          name = "test",
          subschema_key = "name",
          fields = {
            { name = { type = "string", required = true, } },
            { config = { type = "record", abstract = true } },
          }
        })
        assert(Test:new_subschema("my_subschema", {
          fields = {
            { config = {
              type = "record",
              fields = {
                { foo = { type = "string" } },
              },
              default = { foo = "bla" }
            } }
          }
        }))

        local input = {
          name = "my_subschema",
          config = { foo = "hello", bar = "world" },
        }

        local output = Test:process_auto_fields(input, "select")
        input.config.bar = nil
        assert.same(input, output)
      end)
    end)

    describe("#referenceable fields", function()
      lazy_setup(function()
        _G.kong = {
          log   = require "kong.pdk.log".new(),
          vault = require "kong.pdk.vault".new(),
        }
      end)
      lazy_teardown(function()
        _G.kong = nil
        -- clear `_workspaceable` table cache
        package.loaded["kong.db.schema"] = nil
        Schema = require "kong.db.schema"
      end)

      it("dereference string type field", function()
        helpers.setenv("TEST_SECRET_FOO", "foo")
        helpers.setenv("TEST_SECRET_BAR", "bar")
        finally(function()
          helpers.unsetenv("TEST_SECRET_FOO")
          helpers.unsetenv("TEST_SECRET_BAR")
        end)

        local Test = Schema.new({
          fields = {
            {
              secret = {
                type = "string",
                referenceable = true,
              },
            },
          },
        })

        local data = Test:process_auto_fields({
          secret = "{vault://env/test_secret_foo}",
        }, "select")

        assert.same({
          secret = "{vault://env/test_secret_foo}",
        }, data["$refs"])

        assert.equal("foo", data.secret)

        local data = Test:process_auto_fields({
          secret = "{vault://env/test_not_found}",
        }, "select")

        assert.same({
          secret = "{vault://env/test_not_found}",
        }, data["$refs"])

        assert.equal("", data.secret)

        local data = Test:process_auto_fields({
          secret = "{vault://env/test_secret_bar}",
        }, "select")

        assert.same({
          secret = "{vault://env/test_secret_bar}",
        }, data["$refs"])

        assert.equal("bar", data.secret)
      end)

      it("dereference string type field (len_min=0)", function()
        helpers.setenv("TEST_SECRET_FOO", "foo")
        helpers.setenv("TEST_SECRET_BAR", "bar")
        finally(function()
          helpers.unsetenv("TEST_SECRET_FOO")
          helpers.unsetenv("TEST_SECRET_BAR")
        end)

        local Test = Schema.new({
          fields = {
            {
              secret = {
                type = "string",
                len_min = 0,
                referenceable = true,
              },
            },
          },
        })

        local data = Test:process_auto_fields({
          secret = "{vault://env/test_secret_foo}",
        }, "select")

        assert.same({
          secret = "{vault://env/test_secret_foo}",
        }, data["$refs"])

        assert.equal("foo", data.secret)

        local data = Test:process_auto_fields({
          secret = "{vault://env/test_not_found}",
        }, "select")

        assert.same({
          secret = "{vault://env/test_not_found}",
        }, data["$refs"])

        assert.equal("", data.secret)

        local data = Test:process_auto_fields({
          secret = "{vault://env/test_secret_bar}",
        }, "select")

        assert.same({
          secret = "{vault://env/test_secret_bar}",
        }, data["$refs"])

        assert.equal("bar", data.secret)
      end)


      it("dereference array type field", function()
        helpers.setenv("TEST_SECRET_FOO", "foo")
        helpers.setenv("TEST_SECRET_BAR", "bar")
        finally(function()
          helpers.unsetenv("TEST_SECRET_FOO")
          helpers.unsetenv("TEST_SECRET_BAR")
        end)

        local Test = Schema.new({
          fields = {
            {
              secrets = {
                type = "array",
                elements = {
                  type = "string",
                  referenceable = true,
                },
              },
            },
          },
        })

        local data = Test:process_auto_fields({
          secrets = {
            nil,
            "{vault://env/test_secret_foo}",
            "{vault://env/test_not_found}",
            "not a ref",
            "{vault://env/test_secret_bar}",
          },
        }, "select")

        assert.same({
          secrets = {
            nil,
            "{vault://env/test_secret_foo}",
            "{vault://env/test_not_found}",
            nil,
            "{vault://env/test_secret_bar}",
          },
        }, data["$refs"])

        assert.same({ nil, "foo", "", "not a ref", "bar" }, data.secrets)
      end)

      it("dereference set type field", function()
        helpers.setenv("TEST_SECRET_FOO", "foo")
        helpers.setenv("TEST_SECRET_BAR", "bar")
        finally(function()
          helpers.unsetenv("TEST_SECRET_FOO")
          helpers.unsetenv("TEST_SECRET_BAR")
        end)

        local Test = Schema.new({
          fields = {
            {
              secrets = {
                type = "set",
                elements = {
                  type = "string",
                  referenceable = true,
                },
              },
            },
          },
        })

        local data = Test:process_auto_fields({
          secrets = {
            nil,
            "{vault://env/test_secret_foo}",
            "{vault://env/test_not_found}",
            "not a ref",
            "{vault://env/test_secret_bar}",
          },
        }, "select")

        assert.same({
          secrets = {
            nil,
            "{vault://env/test_secret_foo}",
            "{vault://env/test_not_found}",
            nil,
            "{vault://env/test_secret_bar}",
          },
        }, data["$refs"])

        assert.same({ nil, "foo", "", "not a ref", "bar" }, data.secrets)
      end)

      it("dereference map type field", function()
        helpers.setenv("TEST_SECRET_FOO", "foo")
        helpers.setenv("TEST_SECRET_BAR", "bar")
        finally(function()
          helpers.unsetenv("TEST_SECRET_FOO")
          helpers.unsetenv("TEST_SECRET_BAR")
        end)

        local Test = Schema.new({
          fields = {
            {
              secrets = {
                type = "map",
                keys = "string",
                values = {
                  type = "string",
                  referenceable = true,
                },
              },
            },
          },
        })

        local data = Test:process_auto_fields({
          secrets = {
            not_a_ref = "not_a_ref",
            foo = "{vault://env/test_secret_foo}",
            not_found = "{vault://env/test_not_found}",
            bar = "{vault://env/test_secret_bar}",
          },
        }, "select")

        assert.same({
          secrets = {
            foo = "{vault://env/test_secret_foo}",
            not_found = "{vault://env/test_not_found}",
            bar = "{vault://env/test_secret_bar}",
          },
        }, data["$refs"])

        assert.same({
          not_a_ref = "not_a_ref",
          foo = "foo",
          not_found = "",
          bar = "bar",
        }, data.secrets)
      end)
    end)
  end)

  describe("merge_values", function()
    it("should correctly merge records", function()
      local Test = Schema.new({
        name = "test", fields = {
          { config = {
              type = "record",
              fields = {
                foo = { type = "string" },
                bar = { type = "string" }
              }
            }
          },
          { name = { type = "string" }
        }}
      })

      local old_values = {
        name = "test",
        config = { foo = "dog", bar = "cat" },
      }

      local new_values = {
        name = "test",
        config = { foo = "pig" },
      }

      local expected_values = {
        name = "test",
        config = { foo = "pig", bar = "cat" }
      }

      local values = Test:merge_values(new_values, old_values)

      assert.equals(values.config.foo, expected_values.config.foo)
      assert.equals(values.config.bar, expected_values.config.bar)
    end)
  end)

  describe("validate_immutable_fields", function()
    it("returns ok when immutable unset in schema fields", function()
      local test_schema = {
        name = "test",

        fields = {
          { name = { type = "string" }, },
        },
      }
      local entity_to_update = { name = "test1" }
      local db_entity = { name = "test2" }

      local TestEntities = Schema.new(test_schema)
      local ok, _ = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.truthy(ok)
    end)

    it("returns errors when immutable set incoming field being updated", function()
      local test_schema = {
        name = "test",

        fields = {
          { name = { type = "string", immutable = true }, },
          { address = { type = "string", immutable = true }, },
          { email = { type = "string" }, },
        },
      }
      local entity_to_update = { name = "test1", address = "a", email = "a@thing.com" }
      local db_entity = { name = "test2", address = "b", email = "b@thing.com" }

      local TestEntities = Schema.new(test_schema)
      local ok, errors = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.falsy(ok)
      assert.equals(errors.name, 'immutable field cannot be updated')
      assert.equals(errors.address, 'immutable field cannot be updated')
      assert.falsy(errors.email)
    end)

    it("returns ok when immutable set incoming field being updated and value is same", function()
      local test_schema = {
        name = "test",

        fields = {
          { name = { type = "string", immutable = true }, },
        },
      }
      local entity_to_update = { name = "test1" }
      local db_entity = { name = "test1" }

      local TestEntities = Schema.new(test_schema)
      local ok, _ = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.truthy(ok)
    end)

    it("can assess if set type immutable fields are similar", function()
      local test_schema = {
        name = "test",

        fields = {
          { table = { type = "set", immutable = true }, },
        },
      }

      local entity_to_update = { table = { dog = "hello", cat = { bat = "hello", }, }, }
      local db_entity = { table = { dog = "hello", cat = { bat = "hello", }, }, }
      local TestEntities = Schema.new(test_schema)
      local ok, _ = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.truthy(ok)
    end)

    it("can assess if foriegn type immutable fields are similar", function()
      local test_schema = {
        name = "test",

        fields = {
          { entity = { type = "foriegn", immutable = true }, },
        },
      }

      local entity_to_update = { entity = { id = '1' }, }
      local db_entity = { entity = { id = '1' }, }
      local TestEntities = Schema.new(test_schema)
      local ok, _ = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.truthy(ok)
    end)

    it("can assess if array type immutable fields are similar", function()
      local test_schema = {
        name = "test",

        fields = {
          { list = { type = "array", immutable = true }, },
        },
      }

      local entity_to_update = { 'dog', 'bat', 'cat', }
      local db_entity = { 'bat', 'cat', 'dog', }
      local TestEntities = Schema.new(test_schema)
      local ok, _ = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.truthy(ok)
    end)

    it("can assess if set type immutable fields are not similar", function()
      local test_schema = {
        name = "test",

        fields = {
          { table = { type = "set", immutable = true }, },
        },
      }

      local entity_to_update = { table = { dog = "hello", cat = { bat = "hello", }, }, }
      local db_entity = { table = { dog = "hello", cat = { bat = "goodbye", }, }, }
      local TestEntities = Schema.new(test_schema)
      local ok, err = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.falsy(ok)
      assert.equals(err.table, 'immutable field cannot be updated')
    end)

    it("can assess if foriegn type immutable fields are not similar", function()
      local test_schema = {
        name = "test",

        fields = {
          { entity = { type = "foriegn", immutable = true }, },
        },
      }

      local entity_to_update = { entity = { id = '1' }, }
      local db_entity = { entity = { id = '2' }, }
      local TestEntities = Schema.new(test_schema)
      local ok, err = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.falsy(ok)
      assert.equals(err.entity, 'immutable field cannot be updated')
    end)

    it("can assess if array type immutable fields are not similar", function()
      local test_schema = {
        name = "test",

        fields = {
          { list = { type = "array", immutable = true }, },
        },
      }

      local entity_to_update = { list = { 'dog', 'bat', 'cat', }, }
      local db_entity = { list = { 'bat', 'cat', 'rat', }, }
      local TestEntities = Schema.new(test_schema)
      local ok, err = TestEntities:validate_immutable_fields(entity_to_update, db_entity)

      assert.falsy(ok)
      assert.equals(err.list, 'immutable field cannot be updated')
    end)
  end)

  describe("shorthand_fields", function()
    it("converts fields", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { name = { type = "string" } },
        },
        shorthand_fields = {
          {
            username = {
              type = "string",
              func = function(value)
                return {
                  name = value
                }
              end,
            },
          },
        },
      })

      local input = { username = "test1" }
      local output, _ = TestSchema:process_auto_fields(input)
      assert.same({ name = "test1" }, output)
    end)

    it("takes precedence", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { field_A = { type = "string" } },
          { field_B = {
            type = "record",
              fields = {
                { x = { type = "string" } }
              },
          }},
        },
        shorthand_fields = {
          {
            shorthand_A = {
              type = "string",
              func = function(value)
                return {
                  field_A = value
                }
              end,
            },
          },
          {
            shorthand_B = {
              type = "string",
              func = function(value)
                return {
                  field_B = {
                    x = value,
                  },
                }
              end,
            },
          },
        },
      })

      local input = { shorthand_A = "test1", field_A = "ignored",
                      shorthand_B = "test2", field_B = { x = "ignored" } }
      local output, _ = TestSchema:process_auto_fields(input)
      assert.same({ field_A = "test1", field_B = { x = "test2" } }, output)

      -- shorthand value takes precedence if the destination field is null
      local input = { shorthand_A = "overwritten-1", field_A = ngx.null,
                      shorthand_B = "overwritten-2", field_B = { x = ngx.null }}
      local output, _ = TestSchema:process_auto_fields(input)
      assert.same({ field_A = "overwritten-1", field_B = { x = "overwritten-2" }  }, output)
    end)

    describe("with simple 'table_path' reverse mapping", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { new_A = { type = "string" } },
          { new_B = {
            type = "record",
            fields = {
              { x = { type = "string" } }
            },
          }},
          { new_C = { type = "string", default = "abc", required = true }},
          { new_D_1 = { type = "string" }},
          { new_D_2 = { type = "string" }},
        },
        shorthand_fields = {
          {
            old_A = {
              type = "string",
              func = function(value)
                return {
                  new_A = value
                }
              end,
              deprecation = {
                replaced_with = { { path = { "new_A" } } },
                message = "old_A is deprecated, please use new_A instead",
                removal_in_version = "4.0",
              },
            },
          },
          {
            old_B = {
              type = "string",
              func = function(value)
                return {
                  new_B = {
                    x = value,
                  },
                }
              end,
              deprecation = {
                replaced_with = { { path = { "new_B", "x" } } },
                message = "old_B is deprecated, please use new_B.x instead",
                removal_in_version = "4.0",
              },
            },
          },
          {
            old_C = {
              type = "string",
              func = function(value)
                return {
                  new_C = value
                }
              end,
              deprecation = {
                replaced_with = { { path = { "new_C" } } },
                message = "old_C is deprecated, please use new_C instead",
                removal_in_version = "4.0",
              }
            }
          },
          {
            old_D = {
              type = "string",
              func = function(value)
                return { new_D_1 = value, new_D_2 = value }
              end,
              deprecation = {
                replaced_with = { { path = { "new_D_1" } }, { path = { "new_D_2" } } },
                message = "old_D is deprecated, please use new_D_1 and new_D_2 instead",
                removal_in_version = "4.0",
              }
            }
          }
        },
      })

      it("notifes of error if values mismatch with replaced field", function()
        local input = { old_A = "not-test-1", new_A = "test-1",
                        old_B = "not-test-2", new_B = { x = "test-2" },
                        old_C = "abc", new_C = "not-abc",  -- "abc" is the default value
                        old_D = "test-4", new_D_1 = "test-4", new_D_2 = "not-test-4", }
        local output, err = TestSchema:process_auto_fields(input)
        assert.same({
            old_A = 'both deprecated and new field are used but their values mismatch: old_A = not-test-1 vs new_A = test-1',
            old_B = 'both deprecated and new field are used but their values mismatch: old_B = not-test-2 vs new_B.x = test-2' ,
            old_C = 'both deprecated and new field are used but their values mismatch: old_C = abc vs new_C = not-abc',
            old_D = 'both deprecated and new field are used but their values mismatch: old_D = test-4 vs new_D_2 = not-test-4' },
          err
        )
        assert.falsy(output)
      end)

      it("accepts config if both new field and deprecated field defined and their values match", function()
        local input = { old_A = "test-1", new_A = "test-1",
                        old_B = "test-2", new_B = { x = "test-2" },
                        -- "C" field is using default
                        old_D = "test-4", new_D_1 = "test-4", new_D_2 = "test-4", }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({ new_A = "test-1", new_B = { x = "test-2" }, new_C = "abc", new_D_1 = "test-4", new_D_2 = "test-4" }, output)


        local input = { old_A = "test-1", new_A = "test-1",
                        old_B = "test-2", new_B = { x = "test-2" },
                        old_C = "test-3", -- no new field C specified but it has a default which should be ignored
                                          new_D_1 = "test-4-1", new_D_2 = "test-4-2", }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({ new_A = "test-1", new_B = { x = "test-2" }, new_C = "test-3", new_D_1 = "test-4-1", new_D_2 = "test-4-2" }, output)

        -- when new values are null it's still accepted
        local input = { old_A = "test-1", new_A = ngx.null,
                        old_B = "test-2", new_B = { x = ngx.null },
                        old_C = "test-3", new_C = ngx.null,
                        old_D = "test-4", new_D_1 = ngx.null, new_D_2 = ngx.null, }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({new_A = "test-1", new_B = { x = "test-2" }, new_C = "test-3", new_D_1 = "test-4", new_D_2 = "test-4" }, output)

        -- when old values are null it's still accepted
        local input = { old_A = ngx.null, new_A = "test-1",
                        old_B = ngx.null, new_B = { x = "test-2" },
                        old_C = ngx.null, new_C = "test-3",
                        old_D = ngx.null, new_D_1 = "test-4-1", new_D_2 = "test-4-2", }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({ new_A = "test-1", new_B = { x = "test-2" }, new_C = "test-3", new_D_1 = "test-4-1", new_D_2 = "test-4-2" }, output)
      end)

      it("allows to set explicit nulls when only one set of fields was passed", function()
        -- when new values are null it's still accepted
        local input = { new_A = ngx.null,
                        new_B = { x = ngx.null },
                        new_C = ngx.null,
                        new_D_1 = ngx.null, new_D_2 = ngx.null }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({new_A = ngx.null, new_B = { x = ngx.null }, new_C = ngx.null, new_D_1 = ngx.null, new_D_2 = ngx.null}, output)

        -- when old values are null it's still accepted
        local input = { old_A = ngx.null,
                        old_B = ngx.null,
                        old_C = ngx.null,
                        old_D = ngx.null }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({new_A = ngx.null, new_B = { x = ngx.null }, new_C = ngx.null, new_D_1 = ngx.null, new_D_2 = ngx.null}, output)
      end)
    end)

    describe("with complex field reverse_mapping_function", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { new_A = { type = "string" } },
          { new_B = {
            type = "record",
            fields = {
              { x = { type = "string" } }
            },
          }},
          { new_C = {
            type = "array",
            elements = {
              type = "number"
            }
          }}
        },
        shorthand_fields = {
          {
            old_A = {
              type = "string",
              func = function(value)
                if value == ngx.null then
                  return { new_A = ngx.null }
                end
                return { new_A = value:upper() }
              end,
              deprecation = {
                replaced_with = {
                  { path = { "new_A" },
                    reverse_mapping_function = function(data)
                      if data.new_A and data.new_A ~= ngx.null then
                        return data.new_A:lower()
                      end

                      return data.new_A
                    end }
                },
                message = "old_A is deprecated, please use new_A instead",
                removal_in_version = "4.0",
              },
            },
          },
          {
            old_B = {
              type = "string",
              func = function(value)
                if value == ngx.null then
                  return {
                    new_B = {
                      x = ngx.null,
                    },
                  }
                end

                return {
                  new_B = {
                    x = value:upper(),
                  },
                }
              end,
              deprecation = {
                replaced_with = {
                  { path = { "new_B", "x" },
                    reverse_mapping_function = function (data)
                      if data.new_B and data.new_B.x ~= ngx.null then
                        return data.new_B.x:lower()
                      end
                      return ngx.null
                    end
                } },
                message = "old_B is deprecated, please use new_B.x instead",
                removal_in_version = "4.0",
              },
            },
          },
          {
            old_C = {
              type = "array",
              elements = {
                type = "number"
              },
              func = function(value)
                if value == ngx.null then
                  return { new_C = ngx.null }
                end
                local copy = table_copy(value)
                table.sort(copy, function(a,b) return a > b end )
                return { new_C = copy } -- new field is reversed
              end,
              deprecation = {
                replaced_with = {
                  { path = { "new_C" },
                    reverse_mapping_function = function (data)
                      if data.new_C == ngx.null then
                        return ngx.null
                      end

                      local copy = table_copy(data.new_C)
                      table.sort(copy, function(a,b) return a < b end)
                      return copy
                    end
                  },
                }
              }
            }
          }
        },
      })

      it("notifes of error if values mismatch with replaced field", function()
        local input = { old_A = "not-test-1", new_A = "TEST1",
                        old_B = "not-test-2", new_B = { x = "TEST2" },
                        old_C = { 1, 2, 4 },  new_C = { 3, 2, 1 } }
        local output, err = TestSchema:process_auto_fields(input)
        assert.same('both deprecated and new field are used but their values mismatch: old_A = not-test-1 vs new_A = test1', err.old_A)
        assert.same('both deprecated and new field are used but their values mismatch: old_B = not-test-2 vs new_B.x = test2', err.old_B)
        assert.matches('both deprecated and new field are used but their values mismatch: old_C = .+ vs new_C = .+', err.old_C)
        assert.falsy(output)
      end)

      it("accepts config if both new field and deprecated field defined and their values match", function()
        local input = { old_A = "test-1", new_A = "TEST-1",
                        old_B = "test-2", new_B = { x = "TEST-2" },
                        old_C = { 1, 2, 3 }, new_C = { 3, 2, 1 } }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({ new_A = "TEST-1", new_B = { x = "TEST-2" }, new_C = { 3, 2, 1 }}, output)

        -- when new values are null it's still accepted
        local input = { old_A = "test-1", new_A = ngx.null,
                        old_B = "test-2", new_B = { x = ngx.null },
                        old_C = { 1, 2, 3 }, new_C = ngx.null }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({ new_A = "TEST-1", new_B = { x = "TEST-2" }, new_C = { 3, 2, 1 }}, output)

        -- when old values are null it's still accepted
        local input = { old_A = ngx.null, new_A = "TEST-1",
                        old_B = ngx.null, new_B = { x = "TEST-2" },
                        old_C = ngx.null, new_C = { 3, 2, 1 } }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({ new_A = "TEST-1", new_B = { x = "TEST-2" }, new_C = { 3, 2, 1 }}, output)
      end)

      it("allows to set explicit nulls when only one set of fields was passed", function()
        -- when new values are null it's still accepted
        local input = { new_A = ngx.null,
                        new_B = { x = ngx.null },
                        new_C = ngx.null }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({new_A = ngx.null, new_B = { x = ngx.null }, new_C = ngx.null}, output)

        -- when old values are null it's still accepted
        local input = { old_A = ngx.null,
                        old_B = ngx.null,
                        old_C = ngx.null }
        local output, err = TestSchema:process_auto_fields(input)
        assert.is_nil(err)
        assert.same({new_A = ngx.null, new_B = { x = ngx.null }, new_C = ngx.null}, output)
      end)
    end)

    it("can produce multiple fields", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { name = { type = "string" } },
          { address = { type = "string" } },
        },
        shorthand_fields = {
          {
            username = {
              type = "string",
              func = function(value)
                return {
                  name = value,
                  address = value:upper(),
                }
              end,
            },
          },
        },
      })

      local input = { username = "test1" }
      local output, _ = TestSchema:process_auto_fields(input)
      assert.same({ name = "test1", address = "TEST1" }, output)
    end)

    it("type checks", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { name = { type = "string" } },
          { address = { type = "string" } },
        },
        shorthand_fields = {
          {
            username = {
              type = "string",
              func = function(value)
                return {
                  name = value,
                  address = value:upper(),
                }
              end,
            },
          },
        },
      })

      local input = { username = 123 }
      local ok, err = TestSchema:process_auto_fields(input)
      assert.falsy(ok)
      assert.same({ username = "expected a string" }, err)
    end)

    it("accepts arrays", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { name = { type = "string" } },
          { address = { type = "string" } },
        },
        shorthand_fields = {
          {
            user = {
              type = "array",
              elements = { type = "string" },
              func = function(value)
                return {
                  name = value[1] or "mario",
                  address = value[2] or "world",
                }
              end,
            },
          },
        },
      })

      local input = { user = { "luigi", "land" } }
      local output, _ = TestSchema:process_auto_fields(input)
      assert.same({ name = "luigi", address = "land" }, output)
    end)

    it("type checks arrays", function()
      local TestSchema = Schema.new({
        name = "test",
        fields = {
          { name = { type = "string" } },
          { address = { type = "string" } },
        },
        shorthand_fields = {
          {
            user = {
              type = "array",
              elements = { type = "string" },
              func = function(value)
                return {
                  name = value[1] or "mario",
                  address = value[2] or "world",
                }
              end,
            },
          },
        },
      })

      local input = { user = "luigi,land" }
      local ok, err = TestSchema:process_auto_fields(input)
      assert.falsy(ok)
      assert.same({ user = "expected an array" }, err)
    end)
  end)

  describe("get_constraints", function()
    it("returns empty constraints", function()
      local test_schema = {
        name = "test",
        fields = { { name = { type = "string" }, }, },
      }

      local TestEntities = Schema.new(test_schema)
      local constraints = TestEntities:get_constraints()

      assert.are.same({}, constraints)
    end)

    it("returns constraints", function()
      local schema1 = {
        name = "test1",
        fields = { { name = { type = "string" }, }, }
      }
      local schema2 = {
        name = "test2",
        fields = {
          { foreign_reference1 = { type = "foreign", reference = "test1" } },
        },
      }
      local schema3 = {
        name = "test3",
        fields = {
          { foreign_reference2 = { type = "foreign", reference = "test1", on_delete = "cascade" } },
        },
      }

      local Entities1 = Schema.new(schema1)
      assert.is.Truthy(Entities1)
      local Entities2 = Schema.new(schema2)
      assert.is.Truthy(Entities2)
      local Entities3 = Schema.new(schema3)
      assert.is.Truthy(Entities3)
      local constraints = Entities1:get_constraints()
      table.sort(constraints, function(a, b)
        return a.field_name < b.field_name
      end)

      assert.are.same({
        { schema = Entities2, field_name = 'foreign_reference1', on_delete = nil },
        { schema = Entities3, field_name = 'foreign_reference2', on_delete = "cascade" },
      }, constraints)
    end)

    it("merges workspaceable constraints", function()
      local workspace_schema = {
        name = "workspaces",
        fields = { { name = { type = "string" }, }, }
      }
      local schema1 = {
        name = "test4",
        workspaceable = true,
        fields = { { name = { type = "string" }, }, }
      }

      local WorkspaceEntity = Schema.new(workspace_schema)
      assert.is.Truthy(WorkspaceEntity)
      local Entities2 = Schema.new(schema1)
      assert.is.Truthy(Entities2)
      local constraints = WorkspaceEntity:get_constraints()

      assert.are.same({
        test4 = true,
        { schema = Entities2 }
      }, constraints)
    end)
  end)

  for i = 1, 2 do
  describe("transform (" .. SchemaKind[i].name .. ")", function()
    it("transforms entity", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            on_write = function(entity)
              return { name = entity.name:upper() }
            end,
          },
        },
      }
      local entity = { name = "test1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("TEST1", transformed_entity.name)
    end)

    it("transforms entity on write and read", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            on_write = function(entity)
              return { name = entity.name:upper() }
            end,
            on_read = function(entity)
              return { name = entity.name:lower() }
            end,
          },
        },
      }
      local entity = { name = "TeSt1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("TEST1", transformed_entity.name)

      transformed_entity, _ = TestEntities:transform(transformed_entity, nil, "select")

      assert.truthy(transformed_entity)
      assert.equal("test1", transformed_entity.name)
    end)

    it("transforms fields", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            on_write = function(name)
              return { name = name:upper() }
            end,
          },
        },
      }
      local entity = { name = "test1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("TEST1", transformed_entity.name)
    end)

    it("transforms fields on write and read", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            on_write = function(name)
              return { name = name:upper() }
            end,
            on_read = function(name)
              return { name = name:lower() }
            end,
          },
        },
      }
      local entity = { name = "TeSt1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("TEST1", transformed_entity.name)

      transformed_entity, _ = TestEntities:transform(transformed_entity, nil, "select")

      assert.truthy(transformed_entity)
      assert.equal("test1", transformed_entity.name)
    end)

    it("transforms fields with input table", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            on_write = function(name)
              return { name = name:upper() }
            end,
          },
        },
      }
      local entity = { name = "test1" }
      local input = { name = "we have a value" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity, input)

      assert.truthy(transformed_entity)
      assert.equal("TEST1", transformed_entity.name)
    end)

    it("skips transformation when none of input matches", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            input = { "non_existent" },
            on_write = function(non_existent)
              return { name = non_existent:upper() }
            end,
          },
        },
      }
      local entity = { name = "test1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("test1", transformed_entity.name)
    end)

    it("skips transformation when none of input matches using input table", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            on_write = function(non_existent)
              return { name = non_existent:upper() }
            end,
          },
        },
      }
      local entity = { name = "test1" }
      local input = { name = nil }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity, input)

      assert.truthy(transformed_entity)
      assert.equal("test1", transformed_entity.name)
    end)

    it("transforms entity with multiple transformations", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            on_write = function(entity)
              return { name = "How are you " .. entity.name }
            end,
          },
          {
            on_write = function(entity)
              return { name = entity.name .. "?" }
            end,
          },
        },
      }

      local entity = { name = "Bob" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("How are you Bob?", transformed_entity.name)
    end)

    it("transforms fields with multiple transformations", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            on_write = function(name)
              return { name = "How are you " .. name }
            end,
          },
          {
            input = { "name" },
            on_write = function(name)
              return { name = name .. "?" }
            end,
          },
        },
      }

      local entity = { name = "Bob" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("How are you Bob?", transformed_entity.name)
    end)

    it("transforms any field not just those given as an input", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
            age = {
              type = "integer"
            }
          },
        },
        transformations = {
          {
            input = { "name" },
            on_write = function(name)
              return { age = #name }
            end,
          },
        },
      }

      local entity = { name = "Bob" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("Bob", transformed_entity.name)
      assert.equal(3, transformed_entity.age)
    end)

    it("returns error if entity transformation returns an error", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            on_write = function(entity)
              return nil, "unable to transform entity"
            end,
          },
        },
      }
      local entity = { name = "test1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, err = TestEntities:transform(entity)

      assert.falsy(transformed_entity)
      assert.equal("transformation failed: unable to transform entity", err)
    end)

    it("returns error if transformation returns an error", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            on_write = function(name)
              return nil, "unable to transform name"
            end,
          },
        },
      }
      local entity = { name = "test1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, err = TestEntities:transform(entity)

      assert.falsy(transformed_entity)
      assert.equal("transformation failed: unable to transform name", err)
    end)


    it("skips transformation if needs are not fulfilled", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
            age = {
              type = "integer"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            needs = { "age" },
            on_write = function(name, age)
              return { name = name:upper() }
            end,
          },
        },
      }
      local entity = { name = "test1" }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("test1", transformed_entity.name)
    end)


    it("transforms fields with needs given to function", function()
      local test_schema = {
        name = "test",
        fields = {
          {
            name = {
              type = "string"
            },
            age = {
              type = "integer"
            },
          },
        },
        transformations = {
          {
            input = { "name" },
            needs = { "age" },
            on_write = function(name, age)
              return { name = name .. " " .. age }
            end,
          },
        },
      }
      local entity = { name = "John", age = 13 }

      local TestEntities = SchemaKind[i].new(test_schema)
      local transformed_entity, _ = TestEntities:transform(entity)

      assert.truthy(transformed_entity)
      assert.equal("John 13", transformed_entity.name)
    end)
  end)
  end
end)