Question

我正在使用PowerMock编写单元测试，模拟一些util类的行为。为测试类定义一次行为（通过@BeforeClass注释）会导致：

首次测试调用以返回模拟值
第二次测试调用返回实际方法返回值

示例代码：

import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest( {A.class, B.class})
public class TestMockedMethods {

private static B b;

@BeforeClass
public static void setUp() {
    PowerMockito.mockStatic(A.class);
    PowerMockito.when(A.getVal()).thenReturn("X");

    b = PowerMockito.mock(B.class);
    PowerMockito.when(b.getVal()).thenReturn("Y");
}

@Test
public void test1() { // PASS
    Assert.assertEquals("X", A.getVal());
    Assert.assertEquals("Y", b.getVal());
}

@Test
public void test2() { // FAIL
    Assert.assertEquals("X", A.getVal()); // actual="A"
    Assert.assertEquals("Y", b.getVal()); // actual="B"
}

}
class A {
  static String getVal() {
    return "A";
  }
}
class B {
  String getVal() {
    return "B";
  }
}

为什么第二次测试失败的任何想法？

Answer 1

方法PowerMockito.mockStatic(...)调用MockCreator.mock(...)。此方法注册了一个Runnable，将在每次测试后执行：

MockRepository.addAfterMethodRunner(new MockitoStateCleaner());

此runnable清除Mockito的内部状态：

private static class MockitoStateCleaner implements Runnable {
    public void run() {
        clearMockProgress();
        clearConfiguration();
    }

    private void clearMockProgress() {
        clearThreadLocalIn(ThreadSafeMockingProgress.class);
    }

    private void clearConfiguration() {
        clearThreadLocalIn(GlobalConfiguration.class);
    }

    private void clearThreadLocalIn(Class<?> cls) {
        Whitebox.getInternalState(cls, ThreadLocal.class).set(null);
        final Class<?> clazz = ClassLoaderUtil.loadClass(cls, ClassLoader.getSystemClassLoader());
        Whitebox.getInternalState(clazz, ThreadLocal.class).set(null);
    }
}

所以你应该在每次测试之前执行你的setUp。

@Before
public void setUp() {
    PowerMockito.mockStatic(A.class);
    PowerMockito.when(A.getVal()).thenReturn("X");

    b = PowerMockito.mock(B.class);
    PowerMockito.when(b.getVal()).thenReturn("Y");
}

使用PowerMock进行每次测试后，模拟行为会重置

1 个答案: