如何在Golang中测试参数的传递？ [英] How to test the passing of arguments in Golang?

问题描述

package main

import (
    "flag"
    "fmt"
)

func main() {
    passArguments()
}

func passArguments() string {
    username := flag.String("user", "root", "Username for this server")
    flag.Parse()
    fmt.Printf("Your username is %q.", *username)

    usernameToString := *username
    return usernameToString
}

将参数传递给已编译的代码：

Passing an argument to the compiled code:

./ args -user = bla

结果：

您的用户名是 bla

显示已通过的用户名。

the username that has been passed is displayed.

目标：为了防止需要每次手动构建和运行代码是时候测试代码了，目的是编写一个能够测试参数传递的测试。

Aim: in order to prevent that the code needs to be build and run manually every time to test the code the aim is to write a test that is able to test the passing of arguments.

尝试

运行以下测试：

package main

import (
    "os"
    "testing"
)

func TestArgs(t *testing.T) {
    expected := "bla"
    os.Args = []string{"-user=bla"}

    actual := passArguments()

    if actual != expected {
        t.Errorf("Test failed, expected: '%s', got:  '%s'", expected, actual)
    }
}

结果：

Your username is "root".Your username is "root".--- FAIL: TestArgs (0.00s)
    args_test.go:15: Test failed, expected: 'bla', got:  'root'
FAIL
coverage: 87.5% of statements
FAIL    tool    0.008s

问题

看起来 os.Args = [] string {-user = bla 不能将此参数传递给函数，因为结果是 root 而不是 bla

It looks like that the os.Args = []string{"-user=bla is not able to pass this argument to the function as the outcome is root instead of bla

推荐答案

根据我的评论， os.Args 中的第一个值是可执行文件本身的（路径），因此 os.Args = [] string { cmd， -user = bla} 应该可以解决您的问题。您可以从标准套件中查看标志测试

Per my comment, the very first value in os.Args is a (path to) executable itself, so os.Args = []string{"cmd", "-user=bla"} should fix your issue. You can take a look at flag test from the standard package where they're doing something similar.

另外，由于 os.Args 是全局变量，所以可能是个好主意保持测试前的状态，并在测试后恢复状态。类似于链接的测试：

Also, as os.Args is a "global variable", it might be a good idea to keep the state from before the test and restore it after. Similarly to the linked test:

oldArgs := os.Args
defer func() { os.Args = oldArgs }()

这在其他测试（例如检查何时传递的真实参数）时可能有用唤起去测试。

This might be useful where other tests are, for example, examining the real arguments passed when evoking go test.

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