英文:
How to generate unit test coverage when using command line flags in Golang subprocess testing?
问题
我对大部分代码都有单元测试。但是我无法弄清楚如何为主包中的 main() 函数生成单元测试覆盖率。
主函数非常简单。它基本上是一个 select 块。它读取标志，然后要么调用另一个函数/执行某些操作，要么只是在屏幕上打印帮助信息。然而，如果命令行选项没有正确设置，它将以各种错误代码退出。因此，需要进行子进程测试。
我尝试了子进程测试技术，但修改了代码以包含覆盖率标志：
cmd := exec.Command(os.Args[0], "-test.run=TestMain -test.coverprofile=/vagrant/ucover/coverage2.out")
这是原始代码：https://talks.golang.org/2014/testing.slide#23
上面幻灯片的解释：http://youtu.be/ndmB0bj7eyw?t=47m16s
但它没有生成覆盖率文件。我一直没有弄清楚为什么。它确实为执行测试的主进程生成覆盖率文件，但在子进程中执行的任何代码当然不会被标记为已执行。
我试图尽可能实现代码覆盖率。我不确定是否遗漏了什么，或者是否有更简单的方法来做到这一点。或者是否根本不可能。
非常感谢您的帮助。
谢谢
Amer
英文:
I have unit tests for most of our code. But I cannot figure out how to generate unit tests coverage for certain code in main() in main package.
The main function is pretty simple. It is basically a select block. It reads flags, then either call another function/execute something, or simply print help on screen. However, if commandline options are not set correctly, it will exit with various error codes. Hence, the need for sub-process testing.
I tried sub-process testing technique but modified code so that it include flag for coverage:
cmd := exec.Command(os.Args[0], "-test.run=TestMain -test.coverprofile=/vagrant/ucover/coverage2.out")
Here is original code: https://talks.golang.org/2014/testing.slide#23
Explanation of above slide: http://youtu.be/ndmB0bj7eyw?t=47m16s
But it doesn't generate cover profile. I haven't been able to figure out why not. It does generate cover profile for main process executing tests, but any code executed in sub-process, of course, is not marked as executed.
I try to achieve as much code coverage as possible. I am not sure if I am missing something or if there is an easier way to do this. Or if it is just not possible.
Any help is appreciated.
Thanks
Amer
答案1
得分: 6
我采用了另一种方法，不涉及重构main()函数：请参考此提交：
我使用了一个全局（未导出的）变量：
var args []string
然后在main()函数中，除非私有变量args已设置，否则使用os.Args：
a := os.Args[1:]
if args != nil {
a = args
}
flag.CommandLine.Parse(a)
在我的测试中，我可以设置我想要的参数：
args = []string{"-v", "-audit", "_tests/p1/conf/gitolite.conf"}
main()
即使在main()函数上，我仍然实现了100%的代码覆盖率。
英文:
I went with another approach which didn't involve refactoring main(): see this commit:
I use a global (unexported) variable:
var args []string
And then in main(), I use os.Args unless the private var args was set:
a := os.Args[1:]
if args != nil {
a = args
}
flag.CommandLine.Parse(a)
In my test, I can set the parameters I want:
args = []string{"-v", "-audit", "_tests/p1/conf/gitolite.conf"}
main()
And I still achieve a 100% code coverage, even over main().
答案2
得分: 4
我会将需要测试的逻辑从main()中分离出来：
func main() {
start(os.Args)
}
func start(args []string) {
// 旧的main()逻辑
}
这样你就可以对start()进行单元测试，而不会改变os.Args。
英文:
I would factor the logic that needs to be tested out of main():
func main() {
start(os.Args)
}
func start(args []string) {
// old main() logic
}
This way you can unit-test start() without mutating os.Args.
答案3
得分: 1
使用@VonC的解决方案，结合Go 1.11版本，我发现在每次重新定义标志位时，需要重置flag.CommandLine，以避免出现“标志位重定义”恐慌。
for _, check := range checks {
t.Run("flagging " + check.arg, func(t *testing.T) {
flag.CommandLine = flag.NewFlagSet(cmd, flag.ContinueOnError)
args = []string{check.arg}
main()
})
}
英文:
Using @VonC solution with Go 1.11, I found I had to reset flag.CommandLine on each test redefining the flags, to avoid a "flag redefined" panic.:
for _, check := range checks {
t.Run("flagging " + check.arg, func(t *testing.T) {
flag.CommandLine = flag.NewFlagSet(cmd, flag.ContinueOnError)
args = []string{check.arg}
main()
})
}
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