a valid JSON byte slice, when pretty printed, will be indented to enh…

…ance readability.

pp/Format.go

@@ -2,6 +2,7 @@ package pp
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"github.com/adamluzsi/testcase/internal/reflects"
 	"io"
@@ -17,6 +18,12 @@ func Format(v any) string {
 	return formatter{}.Format(v)
 }
 
+var (
+	typeByteSlice    = reflect.TypeOf((*[]byte)(nil)).Elem()
+	typeTimeDuration = reflect.TypeOf((*time.Duration)(nil)).Elem()
+	typeTimeTime     = reflect.TypeOf((*time.Time)(nil)).Elem()
+)
+
 type formatter struct{}
 
 func (f formatter) Format(v any) string {
@@ -36,11 +43,6 @@ type visitor struct {
 	stack       int
 }
 
-var (
-	typeTimeDuration = reflect.TypeOf((*time.Duration)(nil)).Elem()
-	typeTimeTime     = reflect.TypeOf((*time.Time)(nil)).Elem()
-)
-
 func (v *visitor) Visit(w io.Writer, rv reflect.Value, depth int) {
 	defer debugRecover()
 	td, ok := v.recursionGuard(w, rv)
@@ -88,10 +90,10 @@ func (v *visitor) Visit(w io.Writer, rv reflect.Value, depth int) {
 
 	switch rv.Kind() {
 	case reflect.Array, reflect.Slice:
-		if v.tryByteSlice(w, rv) {
+		if v.tryNilSlice(w, rv) {
 			return
 		}
-		if v.tryNilSlice(w, rv) {
+		if v.tryByteSlice(w, rv, depth) {
 			return
 		}
 
@@ -259,12 +261,12 @@ func (v *visitor) visitStructure(w io.Writer, rv reflect.Value, depth int) {
 
 func (v *visitor) newLine(w io.Writer, depth int) {
 	_, _ = w.Write([]byte("\n"))
-	v.indent(w, depth)
+	_, _ = w.Write([]byte(v.indent(depth)))
 }
 
-func (v *visitor) indent(w io.Writer, depth int) {
+func (v *visitor) indent(depth int) string {
 	const defaultIndent = "\t"
-	_, _ = w.Write([]byte(strings.Repeat(defaultIndent, depth)))
+	return strings.Repeat(defaultIndent, depth)
 }
 
 func (v *visitor) sortMapKeys(keys []reflect.Value) {
@@ -288,9 +290,7 @@ func (v *visitor) sortMapKeys(keys []reflect.Value) {
 	})
 }
 
-var typeByteSlice = reflect.TypeOf([]byte{})
-
-func (v *visitor) tryByteSlice(w io.Writer, rv reflect.Value) bool {
+func (v *visitor) tryByteSlice(w io.Writer, rv reflect.Value, depth int) bool {
 	if !rv.Type().ConvertibleTo(typeByteSlice) {
 		return false
 	}
@@ -300,6 +300,13 @@ func (v *visitor) tryByteSlice(w io.Writer, rv reflect.Value) bool {
 		return false
 	}
 
+	if json.Valid(data) {
+		var buf bytes.Buffer
+		if err := json.Indent(&buf, data, v.indent(depth), "\t"); err == nil {
+			data = buf.Bytes()
+		}
+	}
+
 	var (
 		typeName  = v.getTypeName(rv)
 		quoteChar = "`"

pp/Format_test.go

@@ -105,6 +105,29 @@ func TestFormat(t *testing.T) {
 				t.Must.Equal(expected, act(t))
 			})
 		})
+
+		s.And("it has a field which contains a valid JSON", func(s *testcase.Spec) {
+			type T struct {
+				V json.RawMessage
+			}
+			type C struct {
+				Foo string `json:"foo"`
+			}
+			ent := testcase.Let(s, func(t *testcase.T) T {
+				bs, err := json.Marshal(C{Foo: "Charlotte"})
+				t.Must.NoError(err)
+				return T{V: bs}
+			})
+
+			v.Let(s, func(t *testcase.T) any {
+				return ent.Get(t)
+			})
+
+			s.Then("it will print an indentet version of it", func(t *testcase.T) {
+				exp := "pp_test.T{\n\tV: json.RawMessage(`{\n\t\t\"foo\": \"Charlotte\"\n\t}`),\n}"
+				t.Must.Equal(exp, act(t))
+			})
+		})
 	})
 
 	s.When("v is a slice", func(s *testcase.Spec) {
@@ -201,11 +224,31 @@ func TestFormat(t *testing.T) {
 				})
 
 				s.Then("it will print out as a UTF-8 string", func(t *testcase.T) {
-					expected := "json.RawMessage(`{\"foo\":\"bar\"}`)"
+					expected := "json.RawMessage(`{\n\t\"foo\": \"bar\"\n}`)"
 					t.Log(expected)
 					t.Must.Equal(expected, act(t))
 				})
 			})
+
+			s.And("it is a valid JSON", func(s *testcase.Spec) {
+				type T struct {
+					Foo string `json:"foo"`
+				}
+				ent := testcase.Let(s, func(t *testcase.T) T {
+					return T{Foo: t.Random.StringN(8)}
+				})
+				v.Let(s, func(t *testcase.T) any {
+					bs, err := json.Marshal(ent.Get(t))
+					t.Must.NoError(err)
+					return bs
+				})
+
+				s.Then("it will print an indentet version of it", func(t *testcase.T) {
+					exp, err := json.MarshalIndent(ent.Get(t), "", "\t")
+					t.Must.NoError(err)
+					t.Must.Equal(fmt.Sprintf("[]byte(`%s`)", string(exp)), act(t))
+				})
+			})
 		})
 
 		s.And("it implements fmt.Stringer", func(s *testcase.Spec) {