测试无返回值void方法遇Mockito报错且无代码覆盖率的问题

待测试的VaultService方法 #

@Service
public class VaultService {

    private final ProductRepository repository;

    private final DatabaseService databaseService;

    public VaultService(
            @Autowired BuildProperties buildProperties,
            ProductRepository repository,
            DatabaseService databaseService
    ) {
        logger.info("Creating service");

        this.repository = repository;
        this.databaseService = databaseService;
    }

    protected void checkVaultResponseErrors(VaultResponse vaultResponse) {
        if (vaultResponse.responseStatus != ResponseStatus.SUCCESS) {
            vaultResponse.errors.forEach(error -> {
                if (vaultResponse.responseStatus.equals(ResponseStatus.EXCEPTION)) {
                    throw new VaultException(error.getMessage());
                }
                if (vaultResponse.responseStatus.equals(ResponseStatus.FAILURE)) {
                    throw new VaultFailure(error.getMessage());
                }
            });
        }
    }
}

VaultResponse类定义 #

@Getter
@Setter
@JsonInclude(JsonInclude.Include.NON_NULL)
public class VaultResponse {
    @JsonProperty("responseStatus")
    public ResponseStatus responseStatus;

    @JsonProperty("errors")
    public List<Error> errors;
}

当前错误的测试代码 #

@Test
void should_check_vaultResponse_for_errors() {
    VaultService spyService = Mockito.spy(vaultService);
    VaultResponse vaultResponse = new VaultResponse();
    ResponseStatus status = ResponseStatus.SUCCESS;
    List<Error> error = new ArrayList<>();

    vaultResponse.setResponseStatus(status);
    vaultResponse.setErrors(error);

    doThrow(IllegalArgumentException.class)
            .when(spyService).checkVaultResponseErrors(vaultResponse);
    doNothing().when(spyService).checkVaultResponseErrors(vaultResponse);

    verify(spyService, times(1)).checkVaultResponseErrors(vaultResponse);
}

问题分析 #

• 未执行真实方法：测试仅设置Mock行为，未调用spyService.checkVaultResponseErrors(vaultResponse)，真实逻辑完全没运行，自然无代码覆盖率。
• Mock行为冲突：先设置doThrow再设置doNothing，后者覆盖前者，重复设置无意义。
• Spy使用错误：Spy的作用是调用真实方法，却用doNothing跳过逻辑，违背测试初衷。
• 测试场景单一：仅覆盖SUCCESS状态，未覆盖EXCEPTION和FAILURE分支，无法获取完整覆盖率。

修正后的测试代码 #

针对不同逻辑分支编写独立测试用例，确保每个分支都被覆盖：

测试1：SUCCESS状态无异常抛出 #

@Test
void should_not_throw_exception_when_response_status_is_success() {
    // 初始化被测试类，依赖用Mock替代
    VaultService vaultService = new VaultService(
        Mockito.mock(BuildProperties.class),
        Mockito.mock(ProductRepository.class),
        Mockito.mock(DatabaseService.class)
    );
    VaultResponse vaultResponse = new VaultResponse();
    vaultResponse.setResponseStatus(ResponseStatus.SUCCESS);
    vaultResponse.setErrors(new ArrayList<>());

    // 调用真实方法，无异常则测试通过
    vaultService.checkVaultResponseErrors(vaultResponse);
}

测试2：EXCEPTION状态抛出VaultException #

@Test
void should_throw_vault_exception_when_response_status_is_exception() {
    VaultService vaultService = new VaultService(
        Mockito.mock(BuildProperties.class),
        Mockito.mock(ProductRepository.class),
        Mockito.mock(DatabaseService.class)
    );
    VaultResponse vaultResponse = new VaultResponse();
    vaultResponse.setResponseStatus(ResponseStatus.EXCEPTION);
    
    Error testError = new Error();
    testError.setMessage("Test exception error");
    vaultResponse.setErrors(List.of(testError));

    // 验证抛出指定异常及消息
    VaultException exception = Assertions.assertThrows(VaultException.class, 
        () -> vaultService.checkVaultResponseErrors(vaultResponse));
    Assertions.assertEquals("Test exception error", exception.getMessage());
}

测试3：FAILURE状态抛出VaultFailure #

@Test
void should_throw_vault_failure_when_response_status_is_failure() {
    VaultService vaultService = new VaultService(
        Mockito.mock(BuildProperties.class),
        Mockito.mock(ProductRepository.class),
        Mockito.mock(DatabaseService.class)
    );
    VaultResponse vaultResponse = new VaultResponse();
    vaultResponse.setResponseStatus(ResponseStatus.FAILURE);
    
    Error testError = new Error();
    testError.setMessage("Test failure error");
    vaultResponse.setErrors(List.of(testError));

    // 验证抛出指定异常及消息
    VaultFailure failure = Assertions.assertThrows(VaultFailure.class, 
        () -> vaultService.checkVaultResponseErrors(vaultResponse));
    Assertions.assertEquals("Test failure error", failure.getMessage());
}

关键说明 #

• 直接实例化被测试类：无需使用Spy，直接创建VaultService实例（依赖用Mockito Mock），调用真实方法才能覆盖代码逻辑。
• 分场景测试：每个用例仅覆盖一个分支，逻辑清晰，便于定位问题。
• 验证异常行为：针对非SUCCESS状态，通过assertThrows验证异常类型和消息是否符合预期。

内容的提问来源于stack exchange，提问作者pussyCat