tjson: Fix schema comparison (#944)

Closes #907.

internal/tjson/schema.go

@@ -18,7 +18,6 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"reflect"
 	"time"
 
 	"github.com/FerretDB/FerretDB/internal/types"
@@ -123,15 +122,70 @@ var (
 )
 
 // Equal returns true if the schemas are equal.
+// For composite types schemas are equal if their types and subschemas are equal.
+// For scalar types schemas are equal if their types and formats are equal.
 func (s *Schema) Equal(other *Schema) bool {
 	if s == other {
 		return true
 	}
 
-	// TODO compare significant fields only (ignore title, description, etc.)
-	// TODO compare format according to type (for example, for Number, EmptyFormat == Double)
-	// https://github.com/FerretDB/FerretDB/issues/683
-	return reflect.DeepEqual(s, other)
+	if s.Type != other.Type {
+		return false
+	}
+
+	switch s.Type {
+	case Object:
+		// If `s` and `other` are objects, compare their properties.
+		if len(s.Properties) != len(other.Properties) {
+			return false
+		}
+		for k, v := range s.Properties {
+			vOther, ok := other.Properties[k]
+			if !ok {
+				return false
+			}
+			if eq := v.Equal(vOther); !eq {
+				return false
+			}
+		}
+		return true
+	case Array:
+		// If `s` and `other` are arrays, compare their items.
+		if s.Items == nil || other.Items == nil {
+			panic("schema.Equal: array with nil items")
+		}
+		return s.Items.Equal(other.Items)
+	case String, Integer, Number, Boolean:
+		// For scalar types, it's enough to compare their formats.
+		if s.Format == other.Format {
+			return true
+		}
+	default:
+		panic(fmt.Sprintf("schema.Equal: unknown type `%s`", s.Type))
+	}
+
+	// If formats don't match, normalize schemas: empty format is equal to double for numbers and int64 for integers,
+	// see https://docs.tigrisdata.com/overview/schema#data-types.
+	formatS, formatOther := s.Format, other.Format
+	switch s.Type {
+	case Number:
+		if s.Format == EmptyFormat {
+			formatS = Double
+		}
+		if other.Format == EmptyFormat {
+			formatOther = Double
+		}
+	case Integer:
+		if s.Format == EmptyFormat {
+			formatS = Int64
+		}
+		if other.Format == EmptyFormat {
+			formatOther = Int64
+		}
+	case Array, Boolean, Object, String:
+		// do nothing: these types don't have "default" format
+	}
+	return formatS == formatOther
 }
 
 // Marshal returns the JSON encoding of the schema.

internal/tjson/schema_test.go

@@ -67,3 +67,169 @@ func TestSchemaMarshalUnmarshal(t *testing.T) {
 
 	assert.Equal(t, expected, actual)
 }
+
+func TestSchemaEqual(t *testing.T) {
+	t.Parallel()
+
+	caseInt64Schema := Schema{
+		Type:   Integer,
+		Format: Int64,
+	}
+	caseIntEmptySchema := Schema{
+		Type:   Integer,
+		Format: EmptyFormat,
+	}
+	caseDoubleSchema := Schema{
+		Type:   Number,
+		Format: Double,
+	}
+	caseDoubleEmptySchema := Schema{
+		Type:   Number,
+		Format: EmptyFormat,
+	}
+	caseObjectSchema := Schema{
+		Type: Object,
+		Properties: map[string]*Schema{
+			"a":  stringSchema,
+			"42": &caseIntEmptySchema,
+		},
+	}
+	caseObjectSchemaEqual := Schema{
+		Type: Object,
+		Properties: map[string]*Schema{
+			"42": &caseIntEmptySchema,
+			"a":  stringSchema,
+		},
+	}
+	caseObjectSchemaNotEqual := Schema{
+		Type: Object,
+		Properties: map[string]*Schema{
+			"42": &caseIntEmptySchema,
+			"a":  boolSchema,
+		},
+	}
+	caseObjectSchemaKeyMissing := Schema{
+		Type: Object,
+		Properties: map[string]*Schema{
+			"42": &caseIntEmptySchema,
+			"b":  stringSchema,
+		},
+	}
+	caseObjectSchemaEmpty := Schema{
+		Type:       Object,
+		Properties: map[string]*Schema{},
+	}
+	caseArrayDoubleSchema := Schema{
+		Type:  Array,
+		Items: &caseDoubleSchema,
+	}
+	caseArrayDoubleEmptySchema := Schema{
+		Type:  Array,
+		Items: &caseDoubleEmptySchema,
+	}
+	caseArrayObjectsSchema := Schema{
+		Type:  Array,
+		Items: &caseObjectSchema,
+	}
+	caseArrayObjectsSchemaEqual := Schema{
+		Type:  Array,
+		Items: &caseObjectSchemaEqual,
+	}
+	caseArrayObjectsSchemaNotEqual := Schema{
+		Type:  Array,
+		Items: &caseObjectSchemaNotEqual,
+	}
+
+	for name, tc := range map[string]struct {
+		s        *Schema
+		other    *Schema
+		expected bool
+	}{
+		"StringString": {
+			s:        stringSchema,
+			other:    stringSchema,
+			expected: true,
+		},
+		"StringNumber": {
+			s:        stringSchema,
+			other:    doubleSchema,
+			expected: false,
+		},
+		"NumberString": {
+			s:        doubleSchema,
+			other:    stringSchema,
+			expected: false,
+		},
+		"EmptyInt64": {
+			s:        &caseIntEmptySchema,
+			other:    &caseInt64Schema,
+			expected: true,
+		},
+		"Int64Empty": {
+			s:        &caseInt64Schema,
+			other:    &caseIntEmptySchema,
+			expected: true,
+		},
+		"Int64Int32": {
+			s:        &caseInt64Schema,
+			other:    int32Schema,
+			expected: false,
+		},
+		"EmptyInt32": {
+			s:        &caseIntEmptySchema,
+			other:    int32Schema,
+			expected: false,
+		},
+		"DoubleEmpty": {
+			s:        &caseDoubleSchema,
+			other:    &caseDoubleEmptySchema,
+			expected: true,
+		},
+		"ObjectsEqual": {
+			s:        &caseObjectSchema,
+			other:    &caseObjectSchemaEqual,
+			expected: true,
+		},
+		"ObjectsNotEqual": {
+			s:        &caseObjectSchemaEqual,
+			other:    &caseObjectSchemaNotEqual,
+			expected: false,
+		},
+		"ObjectsKeyMissing": {
+			s:        &caseObjectSchema,
+			other:    &caseObjectSchemaKeyMissing,
+			expected: false,
+		},
+		"ObjectsEmpty": {
+			s:        &caseObjectSchema,
+			other:    &caseObjectSchemaEmpty,
+			expected: false,
+		},
+		"ArrayDouble": {
+			s:        &caseArrayDoubleSchema,
+			other:    &caseArrayDoubleEmptySchema,
+			expected: true,
+		},
+		"ArrayObjects": {
+			s:        &caseArrayObjectsSchema,
+			other:    &caseArrayObjectsSchemaEqual,
+			expected: true,
+		},
+		"ArrayObjectsNotEqual": {
+			s:        &caseArrayObjectsSchemaNotEqual,
+			other:    &caseArrayObjectsSchemaEqual,
+			expected: false,
+		},
+		"ArrayObjectsDouble": {
+			s:        &caseArrayObjectsSchema,
+			other:    &caseArrayDoubleSchema,
+			expected: false,
+		},
+	} {
+		tc := tc
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			assert.Equal(t, tc.expected, tc.s.Equal(tc.other))
+		})
+	}
+}