PowerMockito 在 spring boot 中模拟私有方法

Question

我正在尝试在我的 class 测试中模拟一个私有方法，如下所示。

public String processPayment(...) {
    //some lines
    privateMethod(...);
    return "";
}

private Object privateMethod(...) {
    //some lines
    return someObject;
}

现在我需要测试 processPayment 方法和模拟 privateMethod。

我尝试创建上面的 spy class，但是当我做下面的事情时会调用该方法

final DeviceCheckoutServiceImpl spyDeviceCheckoutService = spy(injectedMockBeanOfAboveClass); //@InjectMock in test class
PowerMockito.doReturn(null).when(spyDeviceCheckoutService, "privateMethod", ArgumentMatchers.anyMap()); //method gets called here
spyDeviceCheckoutService.processPayment(...); //private method isn't mocked somehow, and gets called here too

privateMethod 在第 2 行本身被调用。此外，the privateMethod 没有被嘲笑。

也许我以错误的方式创建了间谍对象？不能做 spy(new DeviceCheckoutServiceImpl()); 因为它需要 bean 实例化。

Powermockito 版本：

compile group: 'org.powermock', name: 'powermock-module-junit4', version: '2.0.0'
compile group: 'org.powermock', name: 'powermock-api-mockito2', version: '2.0.0'

让我知道我做错了什么。

Answer 1

在测试class中我们将通过传递对需要测试的class的引用来调用org.powermock.api.mockito.PowerMockito的spy()方法：

MockPrivateMethodExample spy = PowerMockito.spy(mockPrivateMethodExample);

然后我们定义当这个特定的私有方法被调用时我们想要做什么。

PowerMockito.doReturn("Test").when(spy, {$methodName});

MockPrivateMethodExample.java

public class MockPrivateMethodExample {

  public String getDetails() {
    return "Mock private method example: " + iAmPrivate();
  }

  private String iAmPrivate() {
    return new Date().toString();
  }
}

MockPrivateMethodTest.java

@RunWith(PowerMockRunner.class)
@PrepareForTest(MockPrivateMethodExample.class)
public class MockPrivateMethodTest {

  private MockPrivateMethodExample mockPrivateMethodExample;

  // This is the name of the private method which we want to mock
  private static final String METHOD = "iAmPrivate";

  @Test
  public void testPrivateMethod() throws Exception {
    mockPrivateMethodExample = new MockPrivateMethodExample();

    MockPrivateMethodExample spy = PowerMockito.spy(mockPrivateMethodExample);
    PowerMockito.doReturn("Test").when(spy, METHOD);
    String value = spy.getDetails();

    Assert.assertEquals(value, "Mock private method example: Test");
    PowerMockito.verifyPrivate(spy, Mockito.times(1)).invoke(METHOD);
  }
}

此处有更多详细信息：https://examples.javacodegeeks.com/core-java/mockito/mockito-mock-private-method-example-with-powermock/

Answer 2

Mockito 引入了 AdditionalAnswers.delegatesTo 以支持监视 Spring 代理和其他类似的东西：

检查这个问题：https://github.com/mockito/mockito/issues/529#issuecomment-239494581

So instead of spy(proxy) use mock(TestSubject.class, delegatesTo(springProxy)).

However if annotations are need to read, then you'll need mockito 2 beta. Because mockito 1.x uses CGLIB which doesn't copies annotations on the mockito subclass. Mockito 2 uses the great bytebuddy.

Answer 3

问题已解决！忘记在测试 class 上添加 @PrepareForTest(DeviceCheckoutServiceImpl.class)。

PowerMockito 在 spring boot 中模拟私有方法

PowerMockito mock private methods in springboot

spring-boot

junit

mockito

powermock

powermockito