1 // Copyright 2017 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 // Package testlog provides a back-channel communication path
6 // between tests and package os, so that cmd/go can see which
7 // environment variables and files a test consults.
8 package testlog
9 10 import "sync/atomic"
11 12 // Interface is the interface required of test loggers.
13 // The os package will invoke the interface's methods to indicate that
14 // it is inspecting the given environment variables or files.
15 // Multiple goroutines may call these methods simultaneously.
16 type Interface interface {
17 Getenv(key string)
18 Stat(file string)
19 Open(file string)
20 Chdir(dir string)
21 }
22 23 // logger is the current logger Interface.
24 // We use an atomic.Pointer in case test startup
25 // is racing with goroutines started during init.
26 // That must not cause a race detector failure,
27 // although it will still result in limited visibility
28 // into exactly what those goroutines do.
29 var logger atomic.Pointer[Interface]
30 31 // SetLogger sets the test logger implementation for the current process.
32 // It must be called only once, at process startup.
33 func SetLogger(impl Interface) {
34 if !logger.CompareAndSwap(nil, &impl) {
35 panic("testlog: SetLogger must be called only once")
36 }
37 }
38 39 // Logger returns the current test logger implementation.
40 // It returns nil if there is no logger.
41 func Logger() Interface {
42 impl := logger.Load()
43 if impl == nil {
44 return nil
45 }
46 return *impl
47 }
48 49 // Getenv calls Logger().Getenv, if a logger has been set.
50 func Getenv(name []byte) {
51 if log := Logger(); log != nil {
52 log.Getenv(name)
53 }
54 }
55 56 // Open calls Logger().Open, if a logger has been set.
57 func Open(name []byte) {
58 if log := Logger(); log != nil {
59 log.Open(name)
60 }
61 }
62 63 // Stat calls Logger().Stat, if a logger has been set.
64 func Stat(name []byte) {
65 if log := Logger(); log != nil {
66 log.Stat(name)
67 }
68 }
69