在 PowerMock 中注入模拟时出现 NullPointerException

Question

我正在尝试在单例 bean 中模拟私有方法。测试类如下：

import static org.mockito.Matchers.anyObject;
import static org.mockito.Mockito.when;

import java.util.Hashtable;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(SampleBean.class)
public class SampleBeanTest{
    @InjectMocks
    private SampleBean sampleBean = new SampleBean();


    /**
     * Sets the up.
     * @throws Exception the exception
     */
    @Before
    public final void setUp() throws Exception {
        //MockitoAnnotations.initMocks(SampleBean);
        PowerMockito.doReturn("response").when(sampleBean, "privateMethod", anyObject(), DUMMY_QUEUE);
    }

    @Test
    public void testGetData() throws Exception {
        sampleBean.publicMethod();

    }
}

当我运行测试时，我得到以下异常：

java.lang.NullPointerException: null
    at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.addAnswersForStubbing(PowerMockitoStubberImpl.java:68)
    at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.prepareForStubbing(PowerMockitoStubberImpl.java:123)
    at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.when(PowerMockitoStubberImpl.java:91)
    at com.temp.SampleBeanTest.setUp(SampleBeanTest.java:30)

我发现 PowerMock 在以下行返回 null：

MockitoMethodInvocationControl invocationControl = (MockitoMethodInvocationControl) MockRepository.getInstanceMethodInvocationControl(mock);

我不确定这种奇怪行为背后的原因是什么。如果您有任何想法，请告诉我。

Answer 1

看起来sampleBean 为空。

您需要被注释掉的MockitoAnnotations.initMocks 调用，但是像这样：

MockitoAnnotations.initMocks(this);

或者，手动操作：

sampleBean = mock(SampleBean.class);