Add customizable equality compare option

v2/README.md

@@ -136,6 +136,7 @@ func TestNewExample(t *testing.T) {
 | `WithNameSuffix`           | Suffix for fixture files.                                | `.golden`
 | `WithDirPerms`             | Directory permissions for fixtures                       | `0755`
 | `WithFilePerms`            | File permissions for fixtures                            | `0644`
+| `WithEqualFn`              | Custom equal logic to be used                            | None
 | `WithDiffEngine`           | Diff engine to use for diff output                       | `ClassicDiff`
 | `WithDiffFn`               | Custom diff logic to be used                             | None
 | `WithIgnoreTemplateErrors` | Ignore errors from templates                             | `false`

v2/assertions.go

@@ -156,7 +156,7 @@ func (g *Goldie) compare(t *testing.T, name string, actualData []byte) error {
 		return fmt.Errorf("expected %s to be nil", err.Error())
 	}
 
-	if !bytes.Equal(actualData, expectedData) {
+	if !g.equal(actualData, expectedData) {
 		msg := "Result did not match the golden fixture. Diff is below:\n\n"
 		actual := string(actualData)
 		expected := string(expectedData)
@@ -202,7 +202,7 @@ func (g *Goldie) compareTemplate(t *testing.T, name string, data interface{}, ac
 		return newErrMissingKey(fmt.Sprintf("Template error: %s", err.Error()))
 	}
 
-	if !bytes.Equal(actualData, expectedData.Bytes()) {
+	if !g.equal(actualData, expectedData.Bytes()) {
 		msg := "Result did not match the golden fixture. Diff is below:\n\n"
 		actual := string(actualData)
 		expected := expectedData.String()
@@ -218,3 +218,10 @@ func (g *Goldie) compareTemplate(t *testing.T, name string, data interface{}, ac
 
 	return nil
 }
+
+func (g *Goldie) equal(actual, expected []byte) bool {
+	if g.equalFn != nil {
+		return g.equalFn(actual, expected)
+	}
+	return bytes.Equal(actual, expected)
+}

v2/assertions_test.go

@@ -14,34 +14,49 @@ func TestCompare(t *testing.T) {
 		actualData   []byte
 		expectedData []byte
 		update       bool
+		equalfn      EqualFn
 		err          error
 	}{
 		{
 			name:         "example",
 			actualData:   []byte("abc"),
 			expectedData: []byte("abc"),
 			update:       true,
+			equalfn:      nil,
 			err:          nil,
 		},
 		{
 			name:         "example",
 			actualData:   []byte("abc"),
 			expectedData: []byte("abc"),
 			update:       false,
+			equalfn:      nil,
 			err:          &errFixtureNotFound{},
 		},
 		{
 			name:         "example",
 			actualData:   []byte("bc"),
 			expectedData: []byte("abc"),
 			update:       true,
+			equalfn:      nil,
 			err:          &errFixtureMismatch{},
 		},
+		{
+			name:         "custom equalfn",
+			actualData:   []byte("ab"),
+			expectedData: []byte("abc"),
+			update:       true,
+			equalfn: func(actual, expected []byte) bool {
+				return actual[0] == expected[0]
+			},
+			err: nil,
+		},
 		{
 			name:         "nil",
 			actualData:   nil,
 			expectedData: nil,
 			update:       true,
+			equalfn:      nil,
 			err:          nil,
 		},
 	}
@@ -54,6 +69,7 @@ func TestCompare(t *testing.T) {
 			assert.Nil(t, err)
 		}
 
+		g.equalFn = test.equalfn
 		err := g.compare(t, test.name, test.actualData)
 		assert.IsType(t, test.err, err)
 

v2/goldie.go

@@ -80,6 +80,7 @@ type Goldie struct {
 	filePerms      os.FileMode
 	dirPerms       os.FileMode
 
+	equalFn              EqualFn
 	diffEngine           DiffEngine
 	diffFn               DiffFn
 	ignoreTemplateErrors bool

v2/interface.go

@@ -23,6 +23,9 @@ type Tester interface {
 	GoldenFileName(t *testing.T, name string) string
 }
 
+// EqualFn compares if actual and expected are equal.
+type EqualFn func(actual []byte, expected []byte) bool
+
 // DiffFn takes in an actual and expected and will return a diff string
 // representing the differences between the two.
 type DiffFn func(actual string, expected string) string
@@ -68,6 +71,7 @@ type OptionProcessor interface {
 	WithFilePerms(mode os.FileMode) error
 	WithDirPerms(mode os.FileMode) error
 
+	WithEqualFn(fn EqualFn) error
 	WithDiffEngine(engine DiffEngine) error
 	WithDiffFn(fn DiffFn) error
 	WithIgnoreTemplateErrors(ignoreErrors bool) error
@@ -117,6 +121,15 @@ func WithDirPerms(mode os.FileMode) Option {
 	}
 }
 
+// WithEqualFn sets the customized equality comapre function that implements
+// the EqualFn signature.
+//noinspection GoUnusedExportedFunction
+func WithEqualFn(fn EqualFn) Option {
+	return func(o OptionProcessor) error {
+		return o.WithEqualFn(fn)
+	}
+}
+
 // WithDiffEngine sets the `diff` engine that will be used to generate the
 // `diff` text.
 //

v2/options.go

@@ -36,6 +36,13 @@ func (g *Goldie) WithDirPerms(mode os.FileMode) error {
 	return nil
 }
 
+// WithEqualFn sets the customized equality comapre function that implements
+// the EqualFn signature.
+func (g *Goldie) WithEqualFn(fn EqualFn) error {
+	g.equalFn = fn
+	return nil
+}
+
 // WithDiffEngine sets the `diff` engine that will be used to generate the
 // `diff` text.
 func (g *Goldie) WithDiffEngine(engine DiffEngine) error {