Copyright 2017 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 testlog provides a back-channel communication path between tests and package os, so that cmd/go can see which environment variables and files a test consults.
package testlog

import
Interface is the interface required of test loggers. The os package will invoke the interface's methods to indicate that it is inspecting the given environment variables or files. Multiple goroutines may call these methods simultaneously.
type Interface interface {
	Getenv(key string)
	Stat(file string)
	Open(file string)
	Chdir(dir string)
}
logger is the current logger Interface. We use an atomic.Value in case test startup is racing with goroutines started during init. That must not cause a race detector failure, although it will still result in limited visibility into exactly what those goroutines do.
var logger atomic.Value
SetLogger sets the test logger implementation for the current process. It must be called only once, at process startup.
func ( Interface) {
	if logger.Load() != nil {
		panic("testlog: SetLogger must be called only once")
	}
	logger.Store(&)
}
Logger returns the current test logger implementation. It returns nil if there is no logger.
func () Interface {
	 := logger.Load()
	if  == nil {
		return nil
	}
	return *.(*Interface)
}
Getenv calls Logger().Getenv, if a logger has been set.
func ( string) {
	if  := Logger();  != nil {
		.Getenv()
	}
}
Open calls Logger().Open, if a logger has been set.
func ( string) {
	if  := Logger();  != nil {
		.Open()
	}
}
Stat calls Logger().Stat, if a logger has been set.
func ( string) {
	if  := Logger();  != nil {
		.Stat()
	}