PowerMock测试通过然后失败 [英] PowerMock test passes then fails

问题描述

为什么我的单元测试在独立运行时通过，但是在运行多个测试时却失败?

Why are my unit-tests passing when run independently, but fail when running multiple tests?

当我执行单个单元测试时，我的测试将成功模拟并返回预期结果.但是，当我运行所有单元测试时，以前通过的测试将失败.

When I execute a single unit test, my tests will successfully mock and return the expected results. However, when I run all unit-tests my previously passing test will fail.

一次测试运行

shouldDoThisAgain()-通过

shouldDoThisAgain() - Pass

多次测试

shouldDoThis()-通过

shouldDoThis() - Pass

shouldDoThisAgain()-失败

shouldDoThisAgain() - Fail

shouldDoThisAgainAgain()-失败

shouldDoThisAgainAgain() - Fail

我的测试:

@PrepareForTest({OtherMethods.class})
@PowerMockIgnore("javax.management.*")
@RunWith(PowerMockRunner.class)
public class DbTest {
    @Test
    public void shouldDoThis() throws Exception() {
        Dal dalMock = mock(Dal.class)
        PowerMockito.whenNew(Dal.class).withAnyArguments().thenReturn(dalMock)
        List<Result> results = new ArrayList<Result>();
        results.add(new Result(1,2,3));
        when(dalMock.getResults()).thenReturn(results)
        assertTrue(Wrapper.MY_WRAPPER.run()); 
    }
    @Test
    public void shouldDoThisAgain() throws Exception() {
        Dal dalMock = mock(Dal.class)
        PowerMockito.whenNew(Dal.class).withAnyArguments().thenReturn(dalMock)
        List<Result> results = new ArrayList<Result>();
        results.add(new Result(2,3,4));
        when(dalMock.getResults()).thenReturn(results)
        assertTrue(Wrapper.MY_WRAPPER.run());
    }
    @Test
    public void shouldDoThisAgainAgain() throws Exception() {
        Dal dalMock = mock(Dal.class)
        PowerMockito.whenNew(Dal.class).withAnyArguments().thenReturn(dalMock)
        List<Result> results = new ArrayList<Result>();
        results.add(new Result(6,5,3));
        when(dalMock.getResults()).thenReturn(results)
        assertTrue(Wrapper.MY_WRAPPER.run());
    }
}

我的课程:

public class Wrapper {
    // not Runnable
    public static final MyWrapper MY_WRAPPER = new MyWrapper(...){
        @Override
        public boolean run() {
           // returns empty list when the test is alone
           // returns 'results' variable when ran with other tests alone
           List<Result> results = OtherMethods.getDal().getResults();
           return !results.isEmpty()
        }
    };  
}

public class OtherMethods {
     private static final Logger LOGGER = LogManager.getLogger(OtherMethods.class);

     public static Dal dal;

     static Dal getDal() {
         if (dal == null) {
             try {   
                 dal = new Dal();
             } catch (Exception e) {
               LOGGER.fatal("DB Connection could not be created for Geonames");
               LOGGER.fatal(e);
           }
        }
        return dal;
    }
}

推荐答案

我找到了我们项目的解决方案.我编写了一个Logger类，该类调用Android的内部静态Log方法.我的某些测试没有直接测试Log类.当我忽略所有这些选项时，基于powermockito的测试变为绿色.但是，当运行这些其他测试时，基于powermockito的测试将失败.有时.

I found the solution for our project. I wrote a Logger class that calls Android's internal static Log methods. Some of my tests did not directly test the Log class. When I ignored all of them, the powermockito-based tests went green. But when these other tests were run, the powermockito-based ones would fail. Sometimes.

这种方法会失败(片状):

This approach would fail (flaky):

@RunWith(PowerMockRunner.class)
@PrepareForTest({Log.class})    // WARNING: HERE BE DRAGONS!
public class MyTest {

    @Test
    public void testMethodThatDoesNotUseStatics() {
        // ...
    }

    @Test
    public void usesStatics() {
        // ...
    }

}

然后我发现您可以使用@PrepareForTest注释每个测试方法，如下所示:

Then I found out you can annotate each test method with @PrepareForTest, like this:

@RunWith(PowerMockRunner.class)
public class MyTest {

    @Test
    public void testMethodThatDoesNotUseStatics() {
        // ...
    }

    @Test
    @PrepareForTest({Log.class})    // that's the way :)
    public void usesStatics() {
        // ...
    }

}

现在测试再次变为绿色.是的，用于非片状测试！ :)

Now the tests are green again. Yay for non-flaky tests! :)

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