src/pkg/encoding/json/encode_test.go

// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package json

import (
	"bytes"
	"math"
	"reflect"
	"testing"
)

type Optionals struct {
	Sr string `json:"sr"`
	So string `json:"so,omitempty"`
	Sw string `json:"-"`

	Ir int `json:"omitempty"` // actually named omitempty, not an option
	Io int `json:"io,omitempty"`

	Slr []string `json:"slr,random"`
	Slo []string `json:"slo,omitempty"`

	Mr map[string]interface{} `json:"mr"`
	Mo map[string]interface{} `json:",omitempty"`
}

var optionalsExpected = `{
 "sr": "",
 "omitempty": 0,
 "slr": null,
 "mr": {}
}`

func TestOmitEmpty(t *testing.T) {
	var o Optionals
	o.Sw = "something"
	o.Mr = map[string]interface{}{}
	o.Mo = map[string]interface{}{}

	got, err := MarshalIndent(&o, "", " ")
	if err != nil {
		t.Fatal(err)
	}
	if got := string(got); got != optionalsExpected {
		t.Errorf(" got: %s\nwant: %s\n", got, optionalsExpected)
	}
}

type StringTag struct {
	BoolStr bool   `json:",string"`
	IntStr  int64  `json:",string"`
	StrStr  string `json:",string"`
}

var stringTagExpected = `{
 "BoolStr": "true",
 "IntStr": "42",
 "StrStr": "\"xzbit\""
}`

func TestStringTag(t *testing.T) {
	var s StringTag
	s.BoolStr = true
	s.IntStr = 42
	s.StrStr = "xzbit"
	got, err := MarshalIndent(&s, "", " ")
	if err != nil {
		t.Fatal(err)
	}
	if got := string(got); got != stringTagExpected {
		t.Fatalf(" got: %s\nwant: %s\n", got, stringTagExpected)
	}

	// Verify that it round-trips.
	var s2 StringTag
	err = NewDecoder(bytes.NewBuffer(got)).Decode(&s2)
	if err != nil {
		t.Fatalf("Decode: %v", err)
	}
	if !reflect.DeepEqual(s, s2) {
		t.Fatalf("decode didn't match.\nsource: %#v\nEncoded as:\n%s\ndecode: %#v", s, string(got), s2)
	}
}

// byte slices are special even if they're renamed types.
type renamedByte byte
type renamedByteSlice []byte
type renamedRenamedByteSlice []renamedByte

func TestEncodeRenamedByteSlice(t *testing.T) {
	s := renamedByteSlice("abc")
	result, err := Marshal(s)
	if err != nil {
		t.Fatal(err)
	}
	expect := `"YWJj"`
	if string(result) != expect {
		t.Errorf(" got %s want %s", result, expect)
	}
	r := renamedRenamedByteSlice("abc")
	result, err = Marshal(r)
	if err != nil {
		t.Fatal(err)
	}
	if string(result) != expect {
		t.Errorf(" got %s want %s", result, expect)
	}
}

var unsupportedValues = []interface{}{
	math.NaN(),
	math.Inf(-1),
	math.Inf(1),
}

func TestUnsupportedValues(t *testing.T) {
	for _, v := range unsupportedValues {
		if _, err := Marshal(v); err != nil {
			if _, ok := err.(*UnsupportedValueError); !ok {
				t.Errorf("for %v, got %T want UnsupportedValueError", v, err)
			}
		} else {
			t.Errorf("for %v, expected error", v)
		}
	}
}

// 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
}

func TestRefValMarshal(t *testing.T) {
	var s = struct {
		R0 Ref
		R1 *Ref
		V0 Val
		V1 *Val
	}{
		R0: 12,
		R1: new(Ref),
		V0: 13,
		V1: new(Val),
	}
	const want = `{"R0":"ref","R1":"ref","V0":"val","V1":"val"}`
	b, err := 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
}

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