关于java：每次使用PowerMock进行测试后，模拟行为都会重置

Mocking behaviour resets after each test with PowerMock

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

第一次测试调用以返回模拟值
第二次测试返回真实方法的返回值

样例代码：

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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";
}
}

任何想法为什么第二次测试失败了？

方法PowerMockito.mockStatic(...)调用MockCreator.mock(...)。此方法注册一个Runnable，它将在每次测试后执行：

1	MockRepository.addAfterMethodRunner(new MockitoStateCleaner());

这个可运行的清理Mockito的内部状态：

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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);
}
}

因此，您应该在每次测试之前执行setUp。

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@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");
}