feat: improve composition, add .rule macro

Also allow to override `#validate` in modules.

Closes #1

README.md

@@ -27,11 +27,22 @@ This shard follows [Semantic Versioning 2.0.0](https://semver.org/), so see [rel
 
 ## Usage
 
+This shards allows validation composition (i.e. inclusion of modules with custom validations and rules).
+
 ```crystal
 require "validations"
 
+module CustomValidations
+  include Validations
+
+  rule :email do |attr, value, rule|
+    invalidate(attr, "must be an email") unless /@/.match(value)
+  end
+end
+
 struct User
   include Validations
+  include CustomValidations
 
   property name : String
   property email : String
@@ -42,7 +53,7 @@ struct User
   end
 
   validate name, size: (1..16)
-  validate email, size: (6..64), regex: /\w+@\w+\.\w{2,}/
+  validate email, size: (6..64), email: true
   validate @age, gte: 18
 
   # Will not be run if `@nilable.nil?`
@@ -56,12 +67,11 @@ struct User
 end
 
 user = User.new("Vadim", "e-mail", 17)
-pp user.valid?
-# false
+user.valid? # false
 pp user.invalid_attributes
 # {
 #   "name" => ["must have size in (1..16)", "must not be equal to Vadim"],
-#   "email" => ["must have size in (6..64)", "must match /\\w+@\\w+\\.\\w{2,}/"],
+#   "email" => ["must have size in (6..64)", "must be an email"],
 #   "@age" => ["must be greater than or equal to 18"]
 # }
 ```

spec/validations/rules/gt_spec.cr

@@ -0,0 +1,28 @@
+require "../../spec_helper"
+
+record GTObject, x : Int32
+
+struct GTObject
+  include Validations
+  validate x, gt: 5
+end
+
+describe ":gt" do
+  context "when valid" do
+    o = GTObject.new(6)
+
+    it do
+      o.valid?.should be_true
+      o.invalid_attributes.empty?.should be_true
+    end
+  end
+
+  context "when invalid" do
+    o = GTObject.new(5)
+
+    it do
+      o.valid?.should be_false
+      o.invalid_attributes.should eq ({"x" => ["must be greater than 5"]})
+    end
+  end
+end

spec/validations/rules/gte_spec.cr

@@ -0,0 +1,28 @@
+require "../../spec_helper"
+
+record GTEObject, x : Int32
+
+struct GTEObject
+  include Validations
+  validate x, gte: 5
+end
+
+describe ":gte" do
+  context "when valid" do
+    o = GTEObject.new(5)
+
+    it do
+      o.valid?.should be_true
+      o.invalid_attributes.empty?.should be_true
+    end
+  end
+
+  context "when invalid" do
+    o = GTEObject.new(4)
+
+    it do
+      o.valid?.should be_false
+      o.invalid_attributes.should eq ({"x" => ["must be greater than or equal to 5"]})
+    end
+  end
+end

spec/validations/rules/in_spec.cr

@@ -0,0 +1,15 @@
+require "../../spec_helper"
+
+record InObject, x : Int32
+
+struct InObject
+  include Validations
+  validate x, in: {1, 2}
+end
+
+describe ":in" do
+  it do
+    InObject.new(1).valid?.should be_true
+    InObject.new(3).valid?.should be_false
+  end
+end

spec/validations/rules/is_spec.cr

@@ -0,0 +1,15 @@
+require "../../spec_helper"
+
+record IsObject, x : Int32
+
+struct IsObject
+  include Validations
+  validate x, is: 1
+end
+
+describe ":is" do
+  it do
+    IsObject.new(1).valid?.should be_true
+    IsObject.new(2).valid?.should be_false
+  end
+end

spec/validations/rules/lt_spec.cr

@@ -0,0 +1,28 @@
+require "../../spec_helper"
+
+record LTObject, x : Int32
+
+struct LTObject
+  include Validations
+  validate x, lt: 5
+end
+
+describe ":lt" do
+  context "when valid" do
+    o = LTObject.new(4)
+
+    it do
+      o.valid?.should be_true
+      o.invalid_attributes.empty?.should be_true
+    end
+  end
+
+  context "when invalid" do
+    o = LTObject.new(5)
+
+    it do
+      o.valid?.should be_false
+      o.invalid_attributes.should eq ({"x" => ["must be less than 5"]})
+    end
+  end
+end

spec/validations/rules/lte_spec.cr

@@ -0,0 +1,28 @@
+require "../../spec_helper"
+
+record LTEObject, x : Int32
+
+struct LTEObject
+  include Validations
+  validate x, lte: 5
+end
+
+describe ":lte" do
+  context "when valid" do
+    o = LTEObject.new(5)
+
+    it do
+      o.valid?.should be_true
+      o.invalid_attributes.empty?.should be_true
+    end
+  end
+
+  context "when invalid" do
+    o = LTEObject.new(6)
+
+    it do
+      o.valid?.should be_false
+      o.invalid_attributes.should eq ({"x" => ["must be less than or equal to 5"]})
+    end
+  end
+end

spec/validations/rules/regex_spec.cr

@@ -0,0 +1,15 @@
+require "../../spec_helper"
+
+record RegexObject, x : String
+
+struct RegexObject
+  include Validations
+  validate x, regex: /@/
+end
+
+describe ":regex" do
+  it do
+    RegexObject.new("foo@bar").valid?.should be_true
+    RegexObject.new("foo").valid?.should be_false
+  end
+end

spec/validations/rules/size_spec.cr

@@ -0,0 +1,56 @@
+require "../../spec_helper"
+
+record NumberSizeObject, x : String
+record RangeSizeObject, x : String
+
+struct NumberSizeObject
+  include Validations
+  validate x, size: 1
+end
+
+struct RangeSizeObject
+  include Validations
+  validate x, size: (1..2)
+end
+
+describe ":size" do
+  context "with number" do
+    context "when valid" do
+      o = NumberSizeObject.new("a")
+
+      it do
+        o.valid?.should be_true
+        o.invalid_attributes.empty?.should be_true
+      end
+    end
+
+    context "when invalid" do
+      o = NumberSizeObject.new("aa")
+
+      it do
+        o.valid?.should be_false
+        o.invalid_attributes.should eq ({"x" => ["must have size equal to 1"]})
+      end
+    end
+  end
+
+  context "with range" do
+    context "when valid" do
+      o = RangeSizeObject.new("a")
+
+      it do
+        o.valid?.should be_true
+        o.invalid_attributes.empty?.should be_true
+      end
+    end
+
+    context "when invalid" do
+      o = RangeSizeObject.new("aaa")
+
+      it do
+        o.valid?.should be_false
+        o.invalid_attributes.should eq ({"x" => ["must have size in 1..2"]})
+      end
+    end
+  end
+end