如何使用mockito和junit测试此函数？

public class UserService {
    private UserRepository userRepository;

    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public User getUserById(int id) {
        return userRepository.findById(id);
    }
}

import static org.mockito.Mockito.*;
import static org.junit.Assert.*;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.junit.MockitoJUnitRunner;

@RunWith(MockitoJUnitRunner.class)
public class UserServiceTest {

    @Mock
    private UserRepository userRepository;

    @InjectMocks
    private UserService userService;

    @Test
    public void testGetUserById() {
        // 创建一个模拟的用户对象
        User mockUser = new User();
        mockUser.setId(1);
        mockUser.setName("Test User");

        // 设置模拟对象的行为
        when(userRepository.findById(1)).thenReturn(mockUser);

        // 调用被测试的方法
        User result = userService.getUserById(1);

        // 验证结果
        assertNotNull(result);
        assertEquals(1, result.getId());
        assertEquals("Test User", result.getName());

        // 验证userRepository.findById方法是否被调用了一次
        verify(userRepository, times(1)).findById(1);
    }
}