在 Java 接口中模拟方法时 Mockito 出现问题

Question

我在使用 Junit5 和 Mockito 3.8 模拟 Java 接口中的方法时遇到问题。测试失败，原因：

Wanted but not invoked:
remoteCommands.getServiceStatus("ABC");
-> at com.acme.CommandHandlerTest.testServiceName(CommandHandlerTest.java:40)
Actually, there were zero interactions with this mock.

它在 CommandHandlerTest.java 的第 40 行失败，即

verify(remoteCommands).getServiceStatus(serviceName);

但是，当我调试代码时，我可以看到正在执行的方法，所以我知道与此方法有 1 次交互，但 Mockito 无法识别它。

如果我遗漏了什么，你能告诉我吗？我的代码文件如下，

CommandHandlerTest.java

package com.acme;

import static org.mockito.ArgumentMatchers.eq;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

import java.rmi.RemoteException;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.jupiter.MockitoExtension;

@ExtendWith(MockitoExtension.class)
public class  CommandHandlerTest {

    private CommandHandler commandHandler;
    
    @Mock
    IRemoteCommandsImpl remoteCommands;
    
    @BeforeEach
    void setup() {
        MockitoAnnotations.openMocks(this);
    }

    @Test
    void testDoCommand_serviceName() throws RemoteException {
        commandHandler = new CommandHandler();
        
        String serviceName = "ABC";
        int mockValue = 4000;

        when(remoteCommands.getServiceStatus(eq(serviceName))).thenReturn(mockValue);
        
        commandHandler.printServiceStatus(serviceName);
        
        verify(remoteCommands).getServiceStatus(serviceName);
        
    }
}

CommandHandler.java

package com.acme;

public class CommandHandler {

    private IRemoteCommands remoteCommands;
    
    public CommandHandler(){

    }

    public void printServiceStatus(String service) {

        remoteCommands = new IRemoteCommandsImpl();
        int serviceStatus = 0;

        try {
            serviceStatus = remoteCommands.getServiceStatus(service);
            System.out.println("CommandHandler->serviceStatus: "+serviceStatus);
        } catch (Exception e) {
            e.getMessage();
        }
    }
}

IRemoteCommands.java

package com.acme;
import java.rmi.Remote;
import java.rmi.RemoteException;

public interface IRemoteCommands extends Remote
{

    public int getServiceStatus(String serviceName) throws RemoteException;

}

IRemoteCommandsImpl.java

package com.acme;
import java.rmi.RemoteException;

public class IRemoteCommandsImpl implements IRemoteCommands{

    @Override
    public int getServiceStatus(String serviceName) throws RemoteException {
        return 1000;
    }
}

Answer 1

在您的 CommandHandler 中，您创建了 IRemoteCommandsImpl 的新实例并将其分配给私有 remoteCommands 字段。

这意味着您模拟的 remoteCommands 未被测试对象使用。

您需要重构您的代码并提供 remoteCommands 给 CommandHandler，最好由构造函数提供：

public class CommandHandler {

    private final IRemoteCommands remoteCommands;
    
    public CommandHandler(IRemoteCommands remoteCommands) {
        this.remoteCommands = remoteCommands;
    }
    // ...
}

最重要的是：

如果您使用 MockitoExtension

MockitoAnnotations.openMocks(this);

在 Java 接口中模拟方法时 Mockito 出现问题

Issue with Mockito when mocking a method in Java Interface

mockito

junit5