使用when（methodX）.thenReturn（resultY），是否会调用methodX？

Question

我在模拟某些单元测试的必要依赖项时遇到了一些困难。我怀疑我没有正确理解如何使用Mockito（）。thenReturn（）。

这是我想要测试的服务的代码（希望是相关的）部分：

@Singleton
public class AppointmentService {
    private DataConnector connector;

    @Inject
    public AppointmentService(DataConnector connector) {
        this.connector = connector;
    }

    public Appointment getAppointment(UriInfo uriInfo, String id) {
        HttpResponse response = connector.getAppointment(id);
        return validateResponse(response, uriInfo);
    }

    protected Appointment validateResponse(HttpResponse response, UriInfo uriInfo) {
        try {
            AppointmentWrapper appointmentWrapper = JacksonJsonUtility.readValue(response.getInputStream(), AppointmentWrapper.class);
            if(appointmentWrapper.getAppointment()!=null) {
                return appointmentConverterHelper(appointmentWrapper.getAppointment(), uriInfo.getPath());
            }
        } catch(IOException e) {
            throw new ResponseParsingException("IOException: " + e.getMessage());
        }
    }

    protected Appointment appointmentConverterHelper(ExternalAppointmentModel appointmentDto, String uriPath) {
        if (appointmentDto == null) {
            throw new BrickworkQueryException("Got an invalid appointment object from Brickwork!");
        }

        Customer customer = new Customer(new Name(appointmentDto.getCustomer().getName()),
            appointmentDto.getCustomer().getEmail(),
            String.valueOf(appointmentDto.getCustomer().getCode()));

        return new Appointment(
            appointmentDto.getId(),
            customer);
    }

}

我的理解是我对这个方法的单元测试应该是这样的：

public class AppointmentServiceTest {

    private UriInfo mockUriInfo;
    private HttpResponse mockHttpResponse;

    @Mock
    private DataConnector mockDataConnector;

    @InjectMocks
    private AppointmentService appointmentService;

    @Before
    public void setUp() throws Exception {
        MockitoAnnotations.initMocks(this);
        mockUriInfo();
        mockHttpResponse();
    }

    private void mockUriInfo() {
        mockUriInfo = mock(UriInfo.class);
        when(mockUriInfo.getRequestUri()).thenReturn(
            URI.create("http://localhost:8080"));
    }

    private void mockHttpResponse() {
        mockHttpResponse = mock(HttpResponse.class);
        when(mockHttpResponse.getInputStream()).thenReturn(
            IOUtils.toInputStream("{\"appointment\":{}}"));
    }

    @Test
    public void testGetAppointment() throws Exception {
        when(mockDataConnector.getAppointmentById(Mockito.anyString())).
            thenReturn(mockHttpResponse);
        when(appointmentService.validateResponse(Mockito.any(HttpResponse.class), Mockito.any(UriInfo.class))).
            thenReturn(new Appointment());
        appointmentService.getAppointment(mockUriInfo, "12345");
        verify(mockDataConnector).getAppointment(Mockito.anyString());
    }
}

当我运行我的测试时，在尝试调用appointmentDto.getCustomer（）时，在appointmentConverterHelper方法中得到NullPointerException，这可以理解为空。由于代码现在正在运行，在我看来，我需要在mockHttpResponse中返回一个包含完全有效的约会的InputStream。因为我when(appointmentService.validateResponse(mockHttpResponse, mockUriInfo)).thenReturn(new Appointment());不应该选择validateResponse调用并返回空的Appointment对象而不是实际运行validateResponse？

作为参考，这里是Exception的堆栈跟踪 - AppointmentServiceTest的第140行是上面的when语句。 AppointmentsService的第176行是JacksonJsonUtility.readValue(response.getInputStream(), AppointmentWrapper.class);方法开头的validateResponse行：

java.lang.NullPointerException
    at com.nike.appointmentservice.service.AppointmentsService.validatedResponse(AppointmentsService.java:176)
    at com.nike.appointmentservice.service.AppointmentsServiceTest.testGetAppointmentById(AppointmentsServiceTest.java:140)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)```

Answer 1

我认为问题可能是when语句试图与特定实例匹配并且失败。要开始使用Mockito单元测试，您应该使用代表“任何内容”的Mockito占位符替换when语句中的特定值。例如：

when(mockDataConnector.getAppointmentById(Mockito.anyString())).
  thenReturn(mockHttpResponse);

when(appointmentService.validateResponse(Mockito.any(HttpResponse.class), Mockito.any(UriInfo.class))).
        thenReturn(new Appointment());

当您进行基本单元测试时，您可以添加更具体的单元测试。

<强>更新

我现在注意到您正在尝试测试AppointmentService类，但您也在嘲笑该类中的validateResponse方法。我不够Mockito专家知道这是否完全不正确，但这不是我在单元测试中使用Mockito的方式。我正在测试的类根本没有被模拟，而是我模拟了它调用的类，以便模拟变量行为并查看测试类如何响应。

我认为您可能需要模拟JacksonJsonUtility类（powermock帮助静态类）并删除validateResponse方法上的模拟。您需要构造对JacksonJsonUtility.readValue方法的模拟响应，使其包含AppointmentService类所期望的所有内容。

Answer 2

基于this post，我认为监视AppointmentService是允许我嘲笑validateResponse电话的方法。所以现在我的测试看起来如何：

public class AppointmentServiceTest {

    private UriInfo mockUriInfo;
    private HttpResponse mockHttpResponse;

    @Mock
    private DataConnector mockDataConnector;

    @Spy
    private AppointmentsService appointmentsServiceSpy;

    @InjectMocks
    private AppointmentService appointmentService;

    @Before
    public void setUp() throws Exception {
        MockitoAnnotations.initMocks(this);
        appointmentsServiceSpy = spy(appointmentsService);
        mockUriInfo();
        mockHttpResponse();
    }

    private void mockUriInfo() {
        mockUriInfo = mock(UriInfo.class);
        when(mockUriInfo.getRequestUri()).thenReturn(
            URI.create("http://localhost:8080"));
    }

    private void mockHttpResponse() {
        mockHttpResponse = mock(HttpResponse.class);
        when(mockHttpResponse.getInputStream()).thenReturn(
            IOUtils.toInputStream("{\"appointment\":{}}"));
    }

    @Test
    public void testGetAppointment() throws Exception {
        when(mockDataConnector.getAppointmentById(Mockito.anyString())).
            thenReturn(mockHttpResponse);
        doReturn(new Appointment()).when(appointmentsServiceSpy).validateResponse(Mockito.any(HttpResponse.class), Mockito.any(UriInfo.class));
        appointmentServiceSpy.getAppointment(mockUriInfo, "12345");
        verify(mockDataConnector).getAppointmentById(Mockito.anyString());
    }
}

我仍然在实际的appointmentServiceSpy.getAppointment电话上获得例外，但我认为这是一个与我如何使用间谍相关的单独问题。出于原始问题的目的，使用带有doReturn().when()语句的间谍可以解决使用when().thenReturn()语句时错误调用的方法问题。