Mockito - 如何模拟方法中实例化的变量？

Question

我有以下Java 方法：

public Appointment addAppointment(String client, Appointment appointment) {

        String esbUrl = new ESBUrlHelper().getEsbUrl();
        AppointmentClient appointmentClient = AppointmentClientFactory.getUnsecuredClient(esbUrl);
        
        if (appointment.getId() == null) {
            outputAppointment = appointmentClient.addAppointment(client, appointment);
        } 

        return outputAppointment;
    }

上述方法调用第三方REST客户端appointmentClient。

我遇到的问题是这导致我的测试失败。

如何在单元测试中模拟 appointmentClientobject？

目前我的测试如下：

@Test
public void shouldAddAppointment() {

    // act
    Appointment appointment = appointmentService.addAppointment(CLIENT_STRING, appointmentMock)

    // assert
    assertNotNull(appointment);
}

但我在appointmentClient.addAppointment(client, appointment); 行收到以下错误：

org.jboss.resteasy.client.exception.ResteasyIOException: IOException
Caused by: java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)

我想模拟如下：

 Mockito.when(appointmentClient.addAppointment(client, appointment)).thenReturn(appointmentMock);

Answer 1

您可以尝试为此使用 PowerMockito。 首先，您需要模拟AppointmentClientFactory 类的静态方法调用，如下所示：

PowerMockito.mockStatic(AppointmentClientFactory.class); 
PowerMockito.when(AppointmentClientFactory,"getUnsecuredClient",esbUrl).thenReturn(appointmentClient);

此外，当您使用 PowerMockito 模拟静态方法时，请将 @PrepareForTest({AppointmentClientFactory.class}) 注释添加到测试类。

Answer 2

使用您当前的代码，模拟对AppointmentClientFactory#getUnsecuredClient 的调用的唯一方法是使用PowerMock，因为工厂方法是静态的。这是由于您的调用代码addAppointment 和此处的依赖项（即AppointmentClientFactory）之间的硬耦合。

如果我是你，我会避免这种情况，因为 PowerMock 不是进行测试的最佳方式。相反，我要做的是将AppointmentClientFactory 作为依赖项注入，从而允许我在测试期间模拟它的一个实例。

这应该是双重方式的最佳方法。首先，因为您实现了不太紧密耦合的代码，其次因为您不需要使用PowerMock 进行单元测试。

Answer 3

使用 Mockito 并非不可能。但是您最初的问题是AppointmentClientFactory 的static 方法。您绝对应该将此方法更改为实例方法（至少为了更好的架构），例如：

 public class AppointmentClientFactory {

    public AppointmentClient getUnsecuredClient(String url) {
        return new AppointmentClient(); //your implementation
    }
 }

那么您的 AppointmentService 将看起来像（或接近它）：

public class AppointmentService {

    private final AppointmentClientFactory factory;

    public AppointmentService() {
        this(new AppointmentClientFactory());
    }

    public AppointmentService(AppointmentClientFactory factory) {
        this.factory = factory;
    }

    public Appointment addAppointment(String client, Appointment appointment) {
        String esbUrl = "";
        Appointment outputAppointment = null;
        AppointmentClient appointmentClient = new AppointmentClientFactory().getUnsecuredClient(esbUrl);
        if (appointment.getId() == null) {
            outputAppointment = appointmentClient.addAppointment(client, appointment);
        }
        return outputAppointment;
    }
}

然后你可以编写如下测试：

public class AppointmentTest {

    private final String CLIENT_STRING = "";

    @Test
    public void shouldAddAppointment() {
        AppointmentClientFactory clientFactory = Mockito.mock(AppointmentClientFactory.class);
        AppointmentClient mockedClient = Mockito.mock(AppointmentClient.class);
        AppointmentService service = new AppointmentService(clientFactory);
        Appointment appointmentMock = new Appointment();
        when(clientFactory.getUnsecuredClient(any())).thenReturn(mockedClient);

        Appointment appointment = service.addAppointment(CLIENT_STRING, appointmentMock);

        assertNotNull(appointment);
    }

}