-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathsilentlybroken_test.go
109 lines (96 loc) · 2.44 KB
/
silentlybroken_test.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
package errutil_test
// This file demonstrates how if you forget to name your return value, even if
// you don't even use a library to handle errors from deferred calls, you have
// a bug only advanced testing will point out.
//
// All the broken* functions below should return the error from mockFile.Close,
// but they don't because they forget to use a named return value.
import (
"errors"
"io"
"sethwklein.net/go/errutil"
"testing"
)
var mockOS = struct {
Create func(string) (io.WriteCloser, error)
}{
func(_ string) (io.WriteCloser, error) {
return mockFile{}, nil
},
}
type mockFile struct{}
var mockError = errors.New("mock error")
func (_ mockFile) Close() error {
return mockError
}
func (_ mockFile) Write(data []byte) (n int, err error) {
return len(data), nil
}
func brokenAppendWriteFile(filename string, data []byte) error {
f, err := mockOS.Create(filename)
if err != nil {
return err
}
defer func() {
err = errutil.Append(err, f.Close())
}()
n, err := f.Write(data)
if err == nil && n < len(data) {
err = io.ErrShortWrite
}
return err
}
func brokenCallWriteFile(filename string, data []byte) error {
f, err := mockOS.Create(filename)
if err != nil {
return err
}
defer errutil.AppendCall(&err, f.Close)
n, err := f.Write(data)
if err == nil && n < len(data) {
err = io.ErrShortWrite
}
return err
}
func brokenManualWriteFile(filename string, data []byte) error {
f, err := mockOS.Create(filename)
if err != nil {
return err
}
defer func() {
e := f.Close()
if e != nil && err == nil {
// This is assumes both errors can't be meaningful
// at the same time which is not guaranteed by the
// method signatures or documentation, although it
// may be guaranteed by the implementation.
err = e
}
}()
n, err := f.Write(data)
if err == nil && n < len(data) {
err = io.ErrShortWrite
}
return err
}
func TestBrokenAppend(t *testing.T) {
err := brokenAppendWriteFile("example.txt", []byte("example!"))
// expected fail
if err != nil { // err != mockError {
t.Errorf("%v != %v", err, mockError)
}
}
func TestBrokenCall(t *testing.T) {
err := brokenCallWriteFile("example.txt", []byte("example!"))
// expected fail
if err != nil { // err != mockError {
t.Errorf("%v != %v", err, mockError)
}
}
func TestBrokenManual(t *testing.T) {
err := brokenManualWriteFile("example.txt", []byte("example!"))
// expected fail
if err != nil { // err != mockError {
t.Errorf("%v != %v", err, mockError)
}
}