Add optional JSON formatting

Author: heppu

file.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/tidwall/pretty"
 )
 
 var DefaultHandler = &FileHandler{
@@ -152,6 +153,15 @@ func NoError(t T, err error, msg string) {
 	}
 }
 
+// EqualWithDiff compares two strings and returns true if they are equal.
+// If they are not equal, test will be marked as failed and the diff will be logged.
 func EqualWithDiff(t T, expected, actual string, msgAndArgs ...interface{}) (ok bool) {
 	return assert.Equal(t, expected, actual, msgAndArgs...)
 }
+
+// PrettyJSON formats the JSON string using the pretty package.
+// This is useful for making the JSON more readable in the golden file
+// also provides cleaner diffs when comparing JSON files.
+func PrettyJSON(t T, data string) string {
+	return string(pretty.Pretty([]byte(data)))
+}

file_test.go

@@ -142,7 +142,7 @@ func TestEqual_No_Match(t *testing.T) {
 	got := golden.Assert(&mt, "other string")
 	assert.False(t, got)
 	assert.Contains(t, mt.msg, "Not equal:")
-	assert.False(t, mt.failed) // In case of assert failure, FailNow is not called
+	assert.True(t, mt.failed)
 }
 
 func TestRequest(t *testing.T) {
@@ -156,6 +156,38 @@ func TestRequest(t *testing.T) {
 	golden.Request(t, http.DefaultClient, req, http.StatusBadRequest)
 }
 
+func TestProcessJSON(t *testing.T) {
+	const (
+		data1 = `{"name": "someone", "age": 41, "active": true}`
+		data2 = `{"name": "someone", "age": 42, "active": true}`
+	)
+
+	fh := &golden.FileHandler{
+		FileName:       golden.TestNameToFilePath,
+		ShouldRecreate: func(t golden.T) bool { return true },
+		Equal:          golden.EqualWithDiff,
+		ProcessContent: golden.PrettyJSON,
+	}
+
+	t.Cleanup(func() { assert.NoError(t, os.RemoveAll("./testdata/TestSomeJSON"), "failed to remove testdata") })
+	mt1 := mockT{name: "TestSomeJSON"}
+	assert.True(t, fh.Assert(&mt1, data1))
+	assert.Empty(t, mt1.msg)
+	assert.False(t, mt1.failed)
+
+	fh.ShouldRecreate = func(t golden.T) bool { return false }
+	mt2 := mockT{name: "TestSomeJSON"}
+	assert.True(t, fh.Assert(&mt2, data1))
+	assert.Empty(t, mt2.msg)
+	assert.False(t, mt2.failed)
+
+	mt3 := mockT{name: "TestSomeJSON"}
+	assert.False(t, fh.Assert(&mt3, data2))
+	assert.Contains(t, mt3.msg, `-  "age": 41,`)
+	assert.Contains(t, mt3.msg, `+  "age": 42,`)
+	assert.True(t, mt3.failed)
+}
+
 func assertResult(t *testing.T, tt test, mt *mockT) {
 	t.Helper()
 	assert.Empty(t, mt.msg)
@@ -172,8 +204,11 @@ type mockT struct {
 	msg    string
 }
 
-func (m *mockT) Name() string                         { return m.name }
-func (m *mockT) Logf(f string, args ...interface{})   { fmt.Printf(f, args...) }
-func (m *mockT) Errorf(f string, args ...interface{}) { m.msg += "\n" + fmt.Sprintf(f, args...) }
-func (m *mockT) FailNow()                             { m.failed = true }
-func (m *mockT) Helper()                              {}
+func (m *mockT) Name() string                       { return m.name }
+func (m *mockT) Logf(f string, args ...interface{}) { fmt.Printf(f, args...) }
+func (m *mockT) FailNow()                           { m.failed = true }
+func (m *mockT) Helper()                            {}
+func (m *mockT) Errorf(f string, args ...interface{}) {
+	m.failed = true
+	m.msg += "\n" + fmt.Sprintf(f, args...)
+}

go.mod

@@ -2,7 +2,10 @@ module github.com/go-tstr/golden
 
 go 1.24.2
 
-require github.com/stretchr/testify v1.10.0
+require (
+	github.com/stretchr/testify v1.10.0
+	github.com/tidwall/pretty v1.2.1
+)
 
 require (
 	4d63.com/gocheckcompilerdirectives v1.3.0 // indirect

go.sum

@@ -575,6 +575,8 @@ github.com/tenntenn/text/transform v0.0.0-20200319021203-7eef512accb3 h1:f+jULpR
 github.com/tenntenn/text/transform v0.0.0-20200319021203-7eef512accb3/go.mod h1:ON8b8w4BN/kE1EOhwT0o+d62W65a6aPw1nouo9LMgyY=
 github.com/tetafro/godot v1.5.1 h1:PZnjCol4+FqaEzvZg5+O8IY2P3hfY9JzRBNPv1pEDS4=
 github.com/tetafro/godot v1.5.1/go.mod h1:cCdPtEndkmqqrhiCfkmxDodMQJ/f3L1BCNskCUZdTwk=
+github.com/tidwall/pretty v1.2.1 h1:qjsOFOWWQl+N3RsoF5/ssm1pHmJJwhjlSbZ51I6wMl4=
+github.com/tidwall/pretty v1.2.1/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
 github.com/timakin/bodyclose v0.0.0-20241222091800-1db5c5ca4d67 h1:9LPGD+jzxMlnk5r6+hJnar67cgpDIz/iyD+rfl5r2Vk=
 github.com/timakin/bodyclose v0.0.0-20241222091800-1db5c5ca4d67/go.mod h1:mkjARE7Yr8qU23YcGMSALbIxTQ9r9QBVahQOBRfU460=
 github.com/timonwong/loggercheck v0.11.0 h1:jdaMpYBl+Uq9mWPXv1r8jc5fC3gyXx4/WGwTnnNKn4M=