go-json/encode_test.go

package json_test

import (
	"errors"
	"fmt"
	"reflect"
	"testing"
	"time"

	"github.com/goccy/go-json"
)

type recursiveT struct {
	A *recursiveT `json:"a,omitempty"`
	B *recursiveU `json:"b,omitempty"`
	C *recursiveU `json:"c,omitempty"`
	D string      `json:"d,omitempty"`
}

type recursiveU struct {
	T *recursiveT `json:"t,omitempty"`
}

func Test_Marshal(t *testing.T) {
	t.Run("int", func(t *testing.T) {
		bytes, err := json.Marshal(-10)
		assertErr(t, err)
		assertEq(t, "int", `-10`, string(bytes))
	})
	t.Run("int8", func(t *testing.T) {
		bytes, err := json.Marshal(int8(-11))
		assertErr(t, err)
		assertEq(t, "int8", `-11`, string(bytes))
	})
	t.Run("int16", func(t *testing.T) {
		bytes, err := json.Marshal(int16(-12))
		assertErr(t, err)
		assertEq(t, "int16", `-12`, string(bytes))
	})
	t.Run("int32", func(t *testing.T) {
		bytes, err := json.Marshal(int32(-13))
		assertErr(t, err)
		assertEq(t, "int32", `-13`, string(bytes))
	})
	t.Run("int64", func(t *testing.T) {
		bytes, err := json.Marshal(int64(-14))
		assertErr(t, err)
		assertEq(t, "int64", `-14`, string(bytes))
	})
	t.Run("uint", func(t *testing.T) {
		bytes, err := json.Marshal(uint(10))
		assertErr(t, err)
		assertEq(t, "uint", `10`, string(bytes))
	})
	t.Run("uint8", func(t *testing.T) {
		bytes, err := json.Marshal(uint8(11))
		assertErr(t, err)
		assertEq(t, "uint8", `11`, string(bytes))
	})
	t.Run("uint16", func(t *testing.T) {
		bytes, err := json.Marshal(uint16(12))
		assertErr(t, err)
		assertEq(t, "uint16", `12`, string(bytes))
	})
	t.Run("uint32", func(t *testing.T) {
		bytes, err := json.Marshal(uint32(13))
		assertErr(t, err)
		assertEq(t, "uint32", `13`, string(bytes))
	})
	t.Run("uint64", func(t *testing.T) {
		bytes, err := json.Marshal(uint64(14))
		assertErr(t, err)
		assertEq(t, "uint64", `14`, string(bytes))
	})
	t.Run("float32", func(t *testing.T) {
		bytes, err := json.Marshal(float32(3.14))
		assertErr(t, err)
		assertEq(t, "float32", `3.14`, string(bytes))
	})
	t.Run("float64", func(t *testing.T) {
		bytes, err := json.Marshal(float64(3.14))
		assertErr(t, err)
		assertEq(t, "float64", `3.14`, string(bytes))
	})
	t.Run("bool", func(t *testing.T) {
		bytes, err := json.Marshal(true)
		assertErr(t, err)
		assertEq(t, "bool", `true`, string(bytes))
	})
	t.Run("string", func(t *testing.T) {
		bytes, err := json.Marshal("hello world")
		assertErr(t, err)
		assertEq(t, "string", `"hello world"`, string(bytes))
	})
	t.Run("struct", func(t *testing.T) {
		bytes, err := json.Marshal(struct {
			A int    `json:"a"`
			B uint   `json:"b"`
			C string `json:"c"`
			D int    `json:"-"`  // ignore field
			a int    `json:"aa"` // private field
		}{
			A: -1,
			B: 1,
			C: "hello world",
		})
		assertErr(t, err)
		assertEq(t, "struct", `{"a":-1,"b":1,"c":"hello world"}`, string(bytes))
		t.Run("null", func(t *testing.T) {
			type T struct {
				A *struct{} `json:"a"`
			}
			var v T
			bytes, err := json.Marshal(&v)
			assertErr(t, err)
			assertEq(t, "struct", `{"a":null}`, string(bytes))
		})
		t.Run("recursive", func(t *testing.T) {
			bytes, err := json.Marshal(recursiveT{
				A: &recursiveT{
					B: &recursiveU{
						T: &recursiveT{
							D: "hello",
						},
					},
					C: &recursiveU{
						T: &recursiveT{
							D: "world",
						},
					},
				},
			})
			assertErr(t, err)
			assertEq(t, "recursive", `{"a":{"b":{"t":{"d":"hello"}},"c":{"t":{"d":"world"}}}}`, string(bytes))
		})
		t.Run("embedded", func(t *testing.T) {
			type T struct {
				A string `json:"a"`
			}
			type U struct {
				*T
				B string `json:"b"`
			}
			type T2 struct {
				A string `json:"a,omitempty"`
			}
			type U2 struct {
				*T2
				B string `json:"b,omitempty"`
			}
			t.Run("exists field", func(t *testing.T) {
				bytes, err := json.Marshal(&U{
					T: &T{
						A: "aaa",
					},
					B: "bbb",
				})
				assertErr(t, err)
				assertEq(t, "embedded", `{"a":"aaa","b":"bbb"}`, string(bytes))
				t.Run("omitempty", func(t *testing.T) {
					bytes, err := json.Marshal(&U2{
						T2: &T2{
							A: "aaa",
						},
						B: "bbb",
					})
					assertErr(t, err)
					assertEq(t, "embedded", `{"a":"aaa","b":"bbb"}`, string(bytes))
				})
			})
			t.Run("none field", func(t *testing.T) {
				bytes, err := json.Marshal(&U{
					B: "bbb",
				})
				assertErr(t, err)
				assertEq(t, "embedded", `{"b":"bbb"}`, string(bytes))
				t.Run("omitempty", func(t *testing.T) {
					bytes, err := json.Marshal(&U2{
						B: "bbb",
					})
					assertErr(t, err)
					assertEq(t, "embedded", `{"b":"bbb"}`, string(bytes))
				})
			})
		})
		t.Run("omitempty", func(t *testing.T) {
			type T struct {
				A int                    `json:",omitempty"`
				B int8                   `json:",omitempty"`
				C int16                  `json:",omitempty"`
				D int32                  `json:",omitempty"`
				E int64                  `json:",omitempty"`
				F uint                   `json:",omitempty"`
				G uint8                  `json:",omitempty"`
				H uint16                 `json:",omitempty"`
				I uint32                 `json:",omitempty"`
				J uint64                 `json:",omitempty"`
				K float32                `json:",omitempty"`
				L float64                `json:",omitempty"`
				O string                 `json:",omitempty"`
				P bool                   `json:",omitempty"`
				Q []int                  `json:",omitempty"`
				R map[string]interface{} `json:",omitempty"`
				S *struct{}              `json:",omitempty"`
				T int                    `json:"t,omitempty"`
			}
			var v T
			v.T = 1
			bytes, err := json.Marshal(&v)
			assertErr(t, err)
			assertEq(t, "struct", `{"t":1}`, string(bytes))
			t.Run("int", func(t *testing.T) {
				var v struct {
					A int `json:"a,omitempty"`
					B int `json:"b"`
				}
				v.B = 1
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "int", `{"b":1}`, string(bytes))
			})
			t.Run("int8", func(t *testing.T) {
				var v struct {
					A int  `json:"a,omitempty"`
					B int8 `json:"b"`
				}
				v.B = 1
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "int8", `{"b":1}`, string(bytes))
			})
			t.Run("int16", func(t *testing.T) {
				var v struct {
					A int   `json:"a,omitempty"`
					B int16 `json:"b"`
				}
				v.B = 1
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "int16", `{"b":1}`, string(bytes))
			})
			t.Run("int32", func(t *testing.T) {
				var v struct {
					A int   `json:"a,omitempty"`
					B int32 `json:"b"`
				}
				v.B = 1
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "int32", `{"b":1}`, string(bytes))
			})
			t.Run("int64", func(t *testing.T) {
				var v struct {
					A int   `json:"a,omitempty"`
					B int64 `json:"b"`
				}
				v.B = 1
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "int64", `{"b":1}`, string(bytes))
			})
			t.Run("string", func(t *testing.T) {
				var v struct {
					A int    `json:"a,omitempty"`
					B string `json:"b"`
				}
				v.B = "b"
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "string", `{"b":"b"}`, string(bytes))
			})
			t.Run("float32", func(t *testing.T) {
				var v struct {
					A int     `json:"a,omitempty"`
					B float32 `json:"b"`
				}
				v.B = 1.1
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "float32", `{"b":1.1}`, string(bytes))
			})
			t.Run("float64", func(t *testing.T) {
				var v struct {
					A int     `json:"a,omitempty"`
					B float64 `json:"b"`
				}
				v.B = 3.14
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "float64", `{"b":3.14}`, string(bytes))
			})
			t.Run("slice", func(t *testing.T) {
				var v struct {
					A int   `json:"a,omitempty"`
					B []int `json:"b"`
				}
				v.B = []int{1, 2, 3}
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "slice", `{"b":[1,2,3]}`, string(bytes))
			})
			t.Run("array", func(t *testing.T) {
				var v struct {
					A int    `json:"a,omitempty"`
					B [2]int `json:"b"`
				}
				v.B = [2]int{1, 2}
				bytes, err := json.Marshal(&v)
				assertErr(t, err)
				assertEq(t, "array", `{"b":[1,2]}`, string(bytes))
			})
			t.Run("map", func(t *testing.T) {
				v := new(struct {
					A int                    `json:"a,omitempty"`
					B map[string]interface{} `json:"b"`
				})
				v.B = map[string]interface{}{"c": 1}
				bytes, err := json.Marshal(v)
				assertErr(t, err)
				assertEq(t, "array", `{"b":{"c":1}}`, string(bytes))
			})
		})
		t.Run("head_omitempty", func(t *testing.T) {
			type T struct {
				A *struct{} `json:"a,omitempty"`
			}
			var v T
			bytes, err := json.Marshal(&v)
			assertErr(t, err)
			assertEq(t, "struct", `{}`, string(bytes))
		})
		t.Run("pointer_head_omitempty", func(t *testing.T) {
			type V struct{}
			type U struct {
				B *V `json:"b,omitempty"`
			}
			type T struct {
				A *U `json:"a"`
			}
			bytes, err := json.Marshal(&T{A: &U{}})
			assertErr(t, err)
			assertEq(t, "struct", `{"a":{}}`, string(bytes))
		})
		t.Run("head_int_omitempty", func(t *testing.T) {
			type T struct {
				A int `json:"a,omitempty"`
			}
			var v T
			bytes, err := json.Marshal(&v)
			assertErr(t, err)
			assertEq(t, "struct", `{}`, string(bytes))
		})
	})
	t.Run("slice", func(t *testing.T) {
		t.Run("[]int", func(t *testing.T) {
			bytes, err := json.Marshal([]int{1, 2, 3, 4})
			assertErr(t, err)
			assertEq(t, "[]int", `[1,2,3,4]`, string(bytes))
		})
		t.Run("[]interface{}", func(t *testing.T) {
			bytes, err := json.Marshal([]interface{}{1, 2.1, "hello"})
			assertErr(t, err)
			assertEq(t, "[]interface{}", `[1,2.1,"hello"]`, string(bytes))
		})
	})

	t.Run("array", func(t *testing.T) {
		bytes, err := json.Marshal([4]int{1, 2, 3, 4})
		assertErr(t, err)
		assertEq(t, "array", `[1,2,3,4]`, string(bytes))
	})
	t.Run("map", func(t *testing.T) {
		t.Run("map[string]int", func(t *testing.T) {
			bytes, err := json.Marshal(map[string]int{
				"a": 1,
				"b": 2,
				"c": 3,
				"d": 4,
			})
			assertErr(t, err)
			assertEq(t, "map", len(`{"a":1,"b":2,"c":3,"d":4}`), len(string(bytes)))
		})
		t.Run("map[string]interface{}", func(t *testing.T) {
			type T struct {
				A int
			}
			v := map[string]interface{}{
				"a": 1,
				"b": 2.1,
				"c": &T{
					A: 10,
				},
				"d": 4,
			}
			bytes, err := json.Marshal(v)
			assertErr(t, err)
			assertEq(t, "map[string]interface{}", len(`{"a":1,"b":2.1,"c":{"A":10},"d":4}`), len(string(bytes)))
		})
	})
}

type marshalJSON struct{}

func (*marshalJSON) MarshalJSON() ([]byte, error) {
	return []byte(`1`), nil
}

func Test_MarshalJSON(t *testing.T) {
	t.Run("*struct", func(t *testing.T) {
		bytes, err := json.Marshal(&marshalJSON{})
		assertErr(t, err)
		assertEq(t, "MarshalJSON", "1", string(bytes))
	})
	t.Run("time", func(t *testing.T) {
		bytes, err := json.Marshal(time.Time{})
		assertErr(t, err)
		assertEq(t, "MarshalJSON", `"0001-01-01T00:00:00Z"`, string(bytes))
	})
}

func Test_MarshalIndent(t *testing.T) {
	prefix := "-"
	indent := "\t"
	t.Run("struct", func(t *testing.T) {
		bytes, err := json.MarshalIndent(struct {
			A int    `json:"a"`
			B uint   `json:"b"`
			C string `json:"c"`
			D int    `json:"-"`  // ignore field
			a int    `json:"aa"` // private field
		}{
			A: -1,
			B: 1,
			C: "hello world",
		}, prefix, indent)
		assertErr(t, err)
		result := "{\n-\t\"a\": -1,\n-\t\"b\": 1,\n-\t\"c\": \"hello world\"\n-}"
		assertEq(t, "struct", result, string(bytes))
	})
	t.Run("slice", func(t *testing.T) {
		t.Run("[]int", func(t *testing.T) {
			bytes, err := json.MarshalIndent([]int{1, 2, 3, 4}, prefix, indent)
			assertErr(t, err)
			result := "[\n-\t1,\n-\t2,\n-\t3,\n-\t4\n-]"
			assertEq(t, "[]int", result, string(bytes))
		})
		t.Run("[]interface{}", func(t *testing.T) {
			bytes, err := json.MarshalIndent([]interface{}{1, 2.1, "hello"}, prefix, indent)
			assertErr(t, err)
			result := "[\n-\t1,\n-\t2.1,\n-\t\"hello\"\n-]"
			assertEq(t, "[]interface{}", result, string(bytes))
		})
	})

	t.Run("array", func(t *testing.T) {
		bytes, err := json.MarshalIndent([4]int{1, 2, 3, 4}, prefix, indent)
		assertErr(t, err)
		result := "[\n-\t1,\n-\t2,\n-\t3,\n-\t4\n-]"
		assertEq(t, "array", result, string(bytes))
	})
	t.Run("map", func(t *testing.T) {
		t.Run("map[string]int", func(t *testing.T) {
			bytes, err := json.MarshalIndent(map[string]int{
				"a": 1,
				"b": 2,
				"c": 3,
				"d": 4,
			}, prefix, indent)
			assertErr(t, err)
			result := "{\n-\t\"a\": 1,\n-\t\"b\": 2,\n-\t\"c\": 3,\n-\t\"d\": 4\n-}"
			assertEq(t, "map", len(result), len(string(bytes)))
		})
		t.Run("map[string]interface{}", func(t *testing.T) {
			type T struct {
				E int
				F int
			}
			v := map[string]interface{}{
				"a": 1,
				"b": 2.1,
				"c": &T{
					E: 10,
					F: 11,
				},
				"d": 4,
			}
			bytes, err := json.MarshalIndent(v, prefix, indent)
			assertErr(t, err)
			result := "{\n-\t\"a\": 1,\n-\t\"b\": 2.1,\n-\t\"c\": {\n-\t\t\"E\": 10,\n-\t\t\"F\": 11\n-\t},\n-\t\"d\": 4\n-}"
			assertEq(t, "map[string]interface{}", len(result), len(string(bytes)))
		})
	})
}

func TestMarshalRawMessageValue(t *testing.T) {
	type (
		T1 struct {
			M json.RawMessage `json:",omitempty"`
		}
		T2 struct {
			M *json.RawMessage `json:",omitempty"`
		}
	)

	var (
		rawNil   = json.RawMessage(nil)
		rawEmpty = json.RawMessage([]byte{})
		rawText  = json.RawMessage([]byte(`"foo"`))
	)

	tests := []struct {
		in   interface{}
		want string
		ok   bool
	}{
		// Test with nil RawMessage.
		{rawNil, "null", true},
		{&rawNil, "null", true},
		{[]interface{}{rawNil}, "[null]", true},
		{&[]interface{}{rawNil}, "[null]", true},
		{[]interface{}{&rawNil}, "[null]", true},
		{&[]interface{}{&rawNil}, "[null]", true},
		{struct{ M json.RawMessage }{rawNil}, `{"M":null}`, true},
		{&struct{ M json.RawMessage }{rawNil}, `{"M":null}`, true},
		{struct{ M *json.RawMessage }{&rawNil}, `{"M":null}`, true},
		{&struct{ M *json.RawMessage }{&rawNil}, `{"M":null}`, true},
		{map[string]interface{}{"M": rawNil}, `{"M":null}`, true},
		{&map[string]interface{}{"M": rawNil}, `{"M":null}`, true},
		{map[string]interface{}{"M": &rawNil}, `{"M":null}`, true},
		{&map[string]interface{}{"M": &rawNil}, `{"M":null}`, true},
		{T1{rawNil}, "{}", true},
		{T2{&rawNil}, `{"M":null}`, true},
		{&T1{rawNil}, "{}", true},
		{&T2{&rawNil}, `{"M":null}`, true},

		// Test with empty, but non-nil, RawMessage.
		{rawEmpty, "", false},
		{&rawEmpty, "", false},
		{[]interface{}{rawEmpty}, "", false},
		{&[]interface{}{rawEmpty}, "", false},
		{[]interface{}{&rawEmpty}, "", false},
		{&[]interface{}{&rawEmpty}, "", false},
		{struct{ X json.RawMessage }{rawEmpty}, "", false},
		{&struct{ X json.RawMessage }{rawEmpty}, "", false},
		{struct{ X *json.RawMessage }{&rawEmpty}, "", false},
		{&struct{ X *json.RawMessage }{&rawEmpty}, "", false},
		{map[string]interface{}{"nil": rawEmpty}, "", false},
		{&map[string]interface{}{"nil": rawEmpty}, "", false},
		{map[string]interface{}{"nil": &rawEmpty}, "", false},
		{&map[string]interface{}{"nil": &rawEmpty}, "", false},

		{T1{rawEmpty}, "{}", true},
		{T2{&rawEmpty}, "", false},
		{&T1{rawEmpty}, "{}", true},
		{&T2{&rawEmpty}, "", false},

		// Test with RawMessage with some text.
		//
		// The tests below marked with Issue6458 used to generate "ImZvbyI=" instead "foo".
		// This behavior was intentionally changed in Go 1.8.
		// See https://golang.org/issues/14493#issuecomment-255857318
		{rawText, `"foo"`, true}, // Issue6458
		{&rawText, `"foo"`, true},
		{[]interface{}{rawText}, `["foo"]`, true},  // Issue6458
		{&[]interface{}{rawText}, `["foo"]`, true}, // Issue6458
		{[]interface{}{&rawText}, `["foo"]`, true},
		{&[]interface{}{&rawText}, `["foo"]`, true},
		{struct{ M json.RawMessage }{rawText}, `{"M":"foo"}`, true}, // Issue6458
		{&struct{ M json.RawMessage }{rawText}, `{"M":"foo"}`, true},
		{struct{ M *json.RawMessage }{&rawText}, `{"M":"foo"}`, true},
		{&struct{ M *json.RawMessage }{&rawText}, `{"M":"foo"}`, true},
		{map[string]interface{}{"M": rawText}, `{"M":"foo"}`, true},  // Issue6458
		{&map[string]interface{}{"M": rawText}, `{"M":"foo"}`, true}, // Issue6458
		{map[string]interface{}{"M": &rawText}, `{"M":"foo"}`, true},
		{&map[string]interface{}{"M": &rawText}, `{"M":"foo"}`, true},
		{T1{rawText}, `{"M":"foo"}`, true}, // Issue6458
		{T2{&rawText}, `{"M":"foo"}`, true},
		{&T1{rawText}, `{"M":"foo"}`, true},
		{&T2{&rawText}, `{"M":"foo"}`, true},
	}

	for i, tt := range tests {
		b, err := json.Marshal(tt.in)
		if ok := (err == nil); ok != tt.ok {
			if err != nil {
				t.Errorf("test %d, unexpected failure: %v", i, err)
			} else {
				t.Errorf("test %d, unexpected success", i)
			}
		}
		if got := string(b); got != tt.want {
			t.Errorf("test %d, Marshal(%#v) = %q, want %q", i, tt.in, got, tt.want)
		}
	}
}

type marshalerError struct{}

func (*marshalerError) MarshalJSON() ([]byte, error) {
	return nil, errors.New("unexpected error")
}

func Test_MarshalerError(t *testing.T) {
	var v marshalerError
	_, err := json.Marshal(&v)
	expect := `json: error calling MarshalJSON for type *json_test.marshalerError: unexpected error`
	assertEq(t, "marshaler error", expect, fmt.Sprint(err))
}

// Ref has Marshaler and Unmarshaler methods with pointer receiver.
type Ref int

func (*Ref) MarshalJSON() ([]byte, error) {
	return []byte(`"ref"`), nil
}

func (r *Ref) UnmarshalJSON([]byte) error {
	*r = 12
	return nil
}

// Val has Marshaler methods with value receiver.
type Val int

func (Val) MarshalJSON() ([]byte, error) {
	return []byte(`"val"`), nil
}

// RefText has Marshaler and Unmarshaler methods with pointer receiver.
type RefText int

func (*RefText) MarshalText() ([]byte, error) {
	return []byte(`"ref"`), nil
}

func (r *RefText) UnmarshalText([]byte) error {
	*r = 13
	return nil
}

// ValText has Marshaler methods with value receiver.
type ValText int

func (ValText) MarshalText() ([]byte, error) {
	return []byte(`"val"`), nil
}

func TestRefValMarshal(t *testing.T) {
	var s = struct {
		R0 Ref
		R1 *Ref
		R2 RefText
		R3 *RefText
		V0 Val
		V1 *Val
		V2 ValText
		V3 *ValText
	}{
		R0: 12,
		R1: new(Ref),
		R2: 14,
		R3: new(RefText),
		V0: 13,
		V1: new(Val),
		V2: 15,
		V3: new(ValText),
	}
	const want = `{"R0":"ref","R1":"ref","R2":"\"ref\"","R3":"\"ref\"","V0":"val","V1":"val","V2":"\"val\"","V3":"\"val\""}`
	b, err := json.Marshal(&s)
	if err != nil {
		t.Fatalf("Marshal: %v", err)
	}
	if got := string(b); got != want {
		t.Errorf("got %q, want %q", got, want)
	}
}

// C implements Marshaler and returns unescaped JSON.
type C int

func (C) MarshalJSON() ([]byte, error) {
	return []byte(`"<&>"`), nil
}

// CText implements Marshaler and returns unescaped text.
type CText int

func (CText) MarshalText() ([]byte, error) {
	return []byte(`"<&>"`), nil
}

func TestMarshalerEscaping(t *testing.T) {
	var c C
	want := `"\u003c\u0026\u003e"`
	b, err := json.Marshal(c)
	if err != nil {
		t.Fatalf("Marshal(c): %v", err)
	}
	if got := string(b); got != want {
		t.Errorf("Marshal(c) = %#q, want %#q", got, want)
	}

	var ct CText
	want = `"\"\u003c\u0026\u003e\""`
	b, err = json.Marshal(ct)
	if err != nil {
		t.Fatalf("Marshal(ct): %v", err)
	}
	if got := string(b); got != want {
		t.Errorf("Marshal(ct) = %#q, want %#q", got, want)
	}
}

type marshalPanic struct{}

func (marshalPanic) MarshalJSON() ([]byte, error) { panic(0xdead) }

func TestMarshalPanic(t *testing.T) {
	defer func() {
		if got := recover(); !reflect.DeepEqual(got, 0xdead) {
			t.Errorf("panic() = (%T)(%v), want 0xdead", got, got)
		}
	}()
	json.Marshal(&marshalPanic{})
	t.Error("Marshal should have panicked")
}

func TestMarshalUncommonFieldNames(t *testing.T) {
	v := struct {
		A0, À, Aβ int
	}{}
	b, err := json.Marshal(v)
	if err != nil {
		t.Fatal("Marshal:", err)
	}
	want := `{"A0":0,"À":0,"Aβ":0}`
	got := string(b)
	if got != want {
		t.Fatalf("Marshal: got %s want %s", got, want)
	}
}

func TestMarshalerError(t *testing.T) {
	s := "test variable"
	st := reflect.TypeOf(s)
	errText := "json: test error"

	tests := []struct {
		err  *json.MarshalerError
		want string
	}{
		{
			json.NewMarshalerError(st, fmt.Errorf(errText), ""),
			"json: error calling MarshalJSON for type " + st.String() + ": " + errText,
		},
		{
			json.NewMarshalerError(st, fmt.Errorf(errText), "TestMarshalerError"),
			"json: error calling TestMarshalerError for type " + st.String() + ": " + errText,
		},
	}

	for i, tt := range tests {
		got := tt.err.Error()
		if got != tt.want {
			t.Errorf("MarshalerError test %d, got: %s, want: %s", i, got, tt.want)
		}
	}
}