1 files changed, 36 insertions, 0 deletions
diff --git a/src/encoding/json/encode_test.go b/src/encoding/json/encode_test.go
index 0b021f0074..c1b9ed2676 100644
--- a/src/encoding/json/encode_test.go
+++ b/src/encoding/json/encode_test.go
@@ -12,6 +12,7 @@ import (
 	"math"
 	"reflect"
 	"regexp"
+	"runtime/debug"
 	"strconv"
 	"testing"
 	"unicode"
@@ -760,6 +761,41 @@ func TestIssue10281(t *testing.T) {
 	}
 }
 
+func TestMarshalErrorAndReuseEncodeState(t *testing.T) {
+	// Disable the GC temporarily to prevent encodeState's in Pool being cleaned away during the test.
+	percent := debug.SetGCPercent(-1)
+	defer debug.SetGCPercent(percent)
+
+	// Trigger an error in Marshal with cyclic data.
+	type Dummy struct {
+		Name string
+		Next *Dummy
+	}
+	dummy := Dummy{Name: "Dummy"}
+	dummy.Next = &dummy
+	if b, err := Marshal(dummy); err == nil {
+		t.Errorf("Marshal(dummy) = %#q; want error", b)
+	}
+
+	type Data struct {
+		A string
+		I int
+	}
+	data := Data{A: "a", I: 1}
+	b, err := Marshal(data)
+	if err != nil {
+		t.Errorf("Marshal(%v) = %v", data, err)
+	}
+
+	var data2 Data
+	if err := Unmarshal(b, &data2); err != nil {
+		t.Errorf("Unmarshal(%v) = %v", data2, err)
+	}
+	if data2 != data {
+		t.Errorf("expect: %v, but get: %v", data, data2)
+	}
+}
+
 func TestHTMLEscape(t *testing.T) {
 	var b, want bytes.Buffer
 	m := `{"M":"<html>foo &` + "\xe2\x80\xa8 \xe2\x80\xa9" + `</html>"}`