如何android单元测试和模拟静态方法 [英] How to android unit test and mock a static method

问题描述

我真的希望你可以帮助我，我觉得我已经把头发拉了好几天。

Hi I really hope you can help me, I feel like I've been pulling my hair out for days.

我正在尝试编写单元测试方法A.方法A调用静态方法B.我想模拟静态方法B.

I'm trying to write unit tests for a method A. Method A calls a static method B. I want to mock static method B.

我知道之前已经问过，但我觉得Android已经成熟了然后，必须有一种方法可以完成这么简单的任务，而无需重新编写我想测试的方法。

I know this has been asked before, but I feel Android has matured since then, and there must be a way to do such a simple task without re-writing the methods I want to test.

这是一个例子，首先是我想要的方法测试：

Here is an example, first the method I want to test:

public String getUserName(Context context, HelperUtils helper) {
    if(helper == null){
        helper = new HelperUtils();
    }
    int currentUserId = helper.fetchUsernameFromInternet(context);

    if (currentUserId == 1) {
        return "Bob";
    } else {
        return "Unknown";
    }
}

接下来我要模拟的静态方法：

Next the static method I want to mock:

public class HelperUtils {
    public static int fetchUsernameFromInternet(Context context) {
        int userid = 0;

        Log.i("HelperUtils ", "hello");

        return userid;
    }
}

在其他语言中这很容易，但我可以不能让它在Android中运行。
我尝试了Mockito，但似乎不支持静态方法

In other languages this is so easy but I just can't make it work in Android. I've tried Mockito, but it appears static methods aren't supported

HelperUtils helper = Mockito.mock(HelperUtils.class);
Mockito.when(helper.fetchUsernameFromInternet(getContext())).thenReturn(1);

此错误

org.mockito.exceptions.misusing.MissingMethodInvocationException

org.mockito.exceptions.misusing.MissingMethodInvocationException

我已经尝试过Powermock但是我不完全确定这是支持的通过Android。我设法在我的gradle文件中使用androidCompile运行powermock但是我收到此错误：

I've tried Powermock but I'm not completely sure this is supported by Android. I managed to get powermock running using androidCompile in my gradle file but I get this error:

错误：任务执行失败'：app： dexDebugAndroidTest。 com.android.ide.common.process.ProcessException：

Error:Execution failed for task ':app:dexDebugAndroidTest'. com.android.ide.common.process.ProcessException:

更不用说 PowerMockito.mockStatic（HelperUtils。 class）; 不返回任何内容，所以我不知道将什么传递给我的getUsername方法！

Not to mention PowerMockito.mockStatic(HelperUtils.class); Doesn't return anything, so I don't know what to pass into my getUsername method!

任何帮助都会如此非常感谢。

Any help would be so very much appreciated.

推荐答案

静态方法与任何对象无关 - 您的 helper.fetchUsernameFromInternet（ ...）与 HelperUtils.fetchUsernameFromInternet（...）相同（但有点令人困惑） - 你甚至应该得到编译器警告由于这个 helper.fetchUsernameFromInternet 。

Static methods aren't related to any object - your helper.fetchUsernameFromInternet(...) is the same (but a bit confusing) as HelperUtils.fetchUsernameFromInternet(...) - you should even get a compiler warning due to this helper.fetchUsernameFromInternet.

而且，而不是 Mockito.mock 模拟你必须使用的静态方法： @RunWith（...）， @PrepareForTest（...）然后 PowerMockito.mockStatic（...） - 完整示例在这里： PowerMockito模拟单个静态方法和返回对象

What's more, instead of Mockito.mock to mock static methods you have to use: @RunWith(...), @PrepareForTest(...) and then PowerMockito.mockStatic(...) - complete example is here: PowerMockito mock single static method and return object

换句话说 - 模拟静态方法（以及构造函数）有点棘手。更好的解决方案是：

In other words - mocking static methods (and also constructors) is a bit tricky. Better solution is:

• 如果你可以改变 HelperUtils ，那就做方法非静态，现在您可以使用通常的 Mockito.mock

• if you can change HelperUtils, make that method non-static and now you can mock HelperUtils with the usual Mockito.mock

如果您无法更改 HelperUtils ，请创建一个包装类，该类委托给原始的 HelperUtils ，但没有静态方法，然后还使用通常的 Mockito.mock （这个想法）有时被称为不要模拟你不拥有的类型。）

if you can't change HelperUtils, create a wrapper class which delegates to the original HelperUtils, but doesn't have static methods, and then also use usual Mockito.mock (this idea is sometimes called "don't mock types you don't own")

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