英文:
How to test code using the Go logging package glog ?
问题
我已经实现了一个包装 glog 的类型，这样我就可以在我的程序中为日志消息添加前缀，以标识日志的发出者，并且我可以根据发出者更改日志级别。
我该如何实现单元测试？问题在于 glog 将文本输出到 stdErr。
代码很简单，但我希望像其他代码一样进行单元测试并实现100%的覆盖率。这个编程工作已经很值得了。
英文:
I have implemented a type wrapping glog so that I can add a prefix to log message identifying the emitter of the log in my program and I can change the log level per emitter.
How could I implement the unit tests ? The problem is that glog outputs text to stdErr.
The code is trivial but I would like the have the unit test and 100% coverage like the rest of the code. This programming effort already payed.
答案1
得分: 4
捕获标准错误的测试代码：
package mainimport ("bytes""io""os""testing""github.com/golang/glog""strings")func captureStderr(f func()) (string, error) {old := os.Stderr // 保存真实的标准错误备份r, w, err := os.Pipe()if err != nil {return "", err}os.Stderr = woutC := make(chan string)// 在单独的goroutine中复制输出，以防止打印阻塞go func() {var buf bytes.Bufferio.Copy(&buf, r)outC <- buf.String()}()// 调用要捕获标准错误的函数：f()// 恢复到正常状态w.Close()os.Stderr = old // 恢复真实的标准错误return <-outC, nil}func TestGlogError(t *testing.T) {stdErr, err := captureStderr(func() {glog.Error("Test error")})if err != nil {t.Errorf("不应该出错，而是出现错误：%+v", err)}if !strings.HasSuffix(strings.TrimSpace(stdErr), "Test error") {t.Errorf("标准错误应该以 'Test error' 结尾，但它并不是：%s", stdErr)}}
运行测试：
go test -v=== RUN TestGlogError--- PASS: TestGlogError (0.00s)PASSok command-line-arguments 0.007s
英文:
Test which captures stderr:
package mainimport ("bytes""io""os""testing""github.com/golang/glog""strings")func captureStderr(f func()) (string, error) {old := os.Stderr // keep backup of the real stderrr, w, err := os.Pipe()if err != nil {return "", err}os.Stderr = woutC := make(chan string)// copy the output in a separate goroutine so printing can't block indefinitelygo func() {var buf bytes.Bufferio.Copy(&buf, r)outC <- buf.String()}()// calling function which stderr we are going to capture:f()// back to normal statew.Close()os.Stderr = old // restoring the real stderrreturn <-outC, nil}func TestGlogError(t *testing.T) {stdErr, err := captureStderr(func() {glog.Error("Test error")})if err != nil {t.Errorf("should not be error, instead: %+v", err)}if !strings.HasSuffix(strings.TrimSpace(stdErr), "Test error") {t.Errorf("stderr should end by 'Test error' but it doesn't: %s", stdErr)}}
running test:
go test -v=== RUN TestGlogError--- PASS: TestGlogError (0.00s)PASSok command-line-arguments 0.007s
答案2
得分: 0
编写一个描述你的用法的接口。如果你使用V方法，这可能不太美观，但是你已经有一个包装器，所以你已经完成了修复这个问题所需的艰苦工作。
对于你需要测试的每个包，定义以下接口：
type Logger interface {Infoln(...interface{}) // 在这个包中实际使用的方法}
然后，你可以通过在代码中不直接引用glog类型来轻松替换它。
英文:
Write an interface that describes your usage. This won't be very pretty if you use the V method, but you have a wrapper so you've already done the hard work that fixing that would entail.
For each package you need to test, define
type Logger interface {Infoln(...interface{}) // the methods you actually use in this package}
And then you can easily swap it out by not referring to glog types directly in your code.
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