1// Copyright (c) 2020 Uber Technologies, Inc.
2//
3// Permission is hereby granted, free of charge, to any person obtaining a copy
4// of this software and associated documentation files (the "Software"), to deal
5// in the Software without restriction, including without limitation the rights
6// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7// copies of the Software, and to permit persons to whom the Software is
8// furnished to do so, subject to the following conditions:
9//
10// The above copyright notice and this permission notice shall be included in
11// all copies or substantial portions of the Software.
12//
13// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
19// THE SOFTWARE.
20
21package atomic
22
23import (
24	"bytes"
25	"io/ioutil"
26	"os"
27	"os/exec"
28	"path/filepath"
29	"reflect"
30	"testing"
31
32	"github.com/stretchr/testify/assert"
33	"github.com/stretchr/testify/require"
34)
35
36func TestNocmpComparability(t *testing.T) {
37	tests := []struct {
38		desc       string
39		give       interface{}
40		comparable bool
41	}{
42		{
43			desc: "nocmp struct",
44			give: nocmp{},
45		},
46		{
47			desc: "struct with nocmp embedded",
48			give: struct{ nocmp }{},
49		},
50		{
51			desc:       "pointer to struct with nocmp embedded",
52			give:       &struct{ nocmp }{},
53			comparable: true,
54		},
55
56		// All exported types must be uncomparable.
57		{desc: "Bool", give: Bool{}},
58		{desc: "Duration", give: Duration{}},
59		{desc: "Error", give: Error{}},
60		{desc: "Float64", give: Float64{}},
61		{desc: "Int32", give: Int32{}},
62		{desc: "Int64", give: Int64{}},
63		{desc: "String", give: String{}},
64		{desc: "Uint32", give: Uint32{}},
65		{desc: "Uint64", give: Uint64{}},
66		{desc: "Value", give: Value{}},
67	}
68
69	for _, tt := range tests {
70		t.Run(tt.desc, func(t *testing.T) {
71			typ := reflect.TypeOf(tt.give)
72			assert.Equalf(t, tt.comparable, typ.Comparable(),
73				"type %v comparablity mismatch", typ)
74		})
75	}
76}
77
78// nocmp must not add to the size of a struct in-memory.
79func TestNocmpSize(t *testing.T) {
80	type x struct{ _ int }
81
82	before := reflect.TypeOf(x{}).Size()
83
84	type y struct {
85		_ nocmp
86		_ x
87	}
88
89	after := reflect.TypeOf(y{}).Size()
90
91	assert.Equal(t, before, after,
92		"expected nocmp to have no effect on struct size")
93}
94
95// This test will fail to compile if we disallow copying of nocmp.
96//
97// We need to allow this so that users can do,
98//
99//   var x atomic.Int32
100//   x = atomic.NewInt32(1)
101func TestNocmpCopy(t *testing.T) {
102	type foo struct{ _ nocmp }
103
104	t.Run("struct copy", func(t *testing.T) {
105		a := foo{}
106		b := a
107		_ = b // unused
108	})
109
110	t.Run("pointer copy", func(t *testing.T) {
111		a := &foo{}
112		b := *a
113		_ = b // unused
114	})
115}
116
117// Fake go.mod with no dependencies.
118const _exampleGoMod = `module example.com/nocmp`
119
120const _badFile = `package atomic
121
122import "fmt"
123
124type Int64 struct {
125	nocmp
126
127	v int64
128}
129
130func shouldNotCompile() {
131	var x, y Int64
132	fmt.Println(x == y)
133}
134`
135
136func TestNocmpIntegration(t *testing.T) {
137	tempdir, err := ioutil.TempDir("", "nocmp")
138	require.NoError(t, err, "unable to set up temporary directory")
139	defer os.RemoveAll(tempdir)
140
141	nocmp, err := ioutil.ReadFile("nocmp.go")
142	require.NoError(t, err, "unable to read nocmp.go")
143
144	require.NoError(t,
145		ioutil.WriteFile(filepath.Join(tempdir, "go.mod"), []byte(_exampleGoMod), 0644),
146		"unable to write go.mod")
147
148	require.NoError(t,
149		ioutil.WriteFile(filepath.Join(tempdir, "nocmp.go"), nocmp, 0644),
150		"unable to write nocmp.go")
151
152	require.NoError(t,
153		ioutil.WriteFile(filepath.Join(tempdir, "bad.go"), []byte(_badFile), 0644),
154		"unable to write bad.go")
155
156	var stderr bytes.Buffer
157	cmd := exec.Command("go", "build")
158	cmd.Dir = tempdir
159	// Create a minimal build enviroment with only HOME set so that "go
160	// build" has somewhere to put the cache and other Go files in.
161	cmd.Env = []string{"HOME=" + filepath.Join(tempdir, "home")}
162	cmd.Stderr = &stderr
163	require.Error(t, cmd.Run(), "bad.go must not compile")
164
165	assert.Contains(t, stderr.String(),
166		"struct containing nocmp cannot be compared")
167}
168