如何使用 Mockito 模拟 HttpClient

Question

这是我正在为其编写 junit 的实际课程。我有 HtpClient 作为私有和最终的。

 public class KMSHttpClientImpl implements KMSHttpClient
 {
/**
 * ObjectMapper Instance.
 */
private final ObjectMapper objectMapper = new ObjectMapper ();

/**
 * KMS ConnectionManager Instance.
 */
private final KMSHttpConnectionManager kmsHttpConnectionManager =
        new KMSHttpConnectionManagerImpl ();

/**
 * HttpClient object.
 */

private final HttpClient httpClient;

/**
 * KMSHttpClient constructor.
 */
public KMSHttpClientImpl ()
{
    // TODO PoolingHttpClientConnectionManager object should be closed after use.
    // TODO This needs to be either singleton or should be kept in static block
    final PoolingHttpClientConnectionManager connectionManager =
            kmsHttpConnectionManager.getConnectionManager();
    httpClient = HttpClients.custom()
            .setConnectionManager(connectionManager)
            .build();
}

@Override
public <T> T invokeGETRequest (final String url, final Class<T> clazz)
        throws KMSClientException
{
    final HttpGet httpGet = new HttpGet(url);
    try {
        final HttpResponse response = httpClient.execute(httpGet);
        return objectMapper.readValue(
                response.getEntity().getContent(), clazz);
    } catch (IOException e) {
        throw new KMSClientException("Unable to get the result", e);
    }
}

@Override
public <T> T invokePOSTRequest (final String url, final Object object, final Class<T> clazz)
        throws KMSClientException
{
    final HttpPost httpPost = new HttpPost(url);
    try {
        final HttpResponse response = httpClient.execute(httpPost);
        return objectMapper.readValue(
                response.getEntity().getContent(), clazz);
    } catch (IOException e) {
        throw new KMSClientException("Unable to create the request", e);
    }
}
 }

这是我的测试课。我正在尝试模拟 HttpClient，但由于它是最终的，我无法模拟它。如果我在我的 KMSHttpClientImpl.java 类中从 HttpClient 中删除 final。我收到 PMd 问题说 可以将私有字段“httpClient”设为最终字段；它仅在声明或构造函数中初始化。我该怎么做才能解决这个问题？

public class KMSHttpClientImplTest
{

/**
 * Injecting mocks KMSHttpClientImpl.
 */
@InjectMocks
private KMSHttpClientImpl kmsHttpClientImpl;

/**
 * Mock HttpClient.
 */
@Mock
private HttpClient httpClient;


/**
 * Initial SetUp Method.
 */
@Before
public void setUp ()
{
    initMocks(this);
}

/**
 * Method to test postRequest Method.
 * @throws KMSClientException
 */
@Test
public void testPostRequest () throws KMSClientException
{
    final OrganizationRequest request = getOrganizationRequest();
    final HttpResponse response = prepareResponse(HttpStatus.SC_OK);
    try {
        Mockito.when(httpClient.execute(Mockito.any())).thenReturn(response);
        final OrganizationResponse organizationResponse = kmsHttpClientImpl.invokePOSTRequest(
                ORG_TEST_URL, request, OrganizationResponse.class);
        assertEquals("Id should match", ORG_ID, organizationResponse.getId());
    } catch (IOException e) {
        throw new KMSClientException("Unable to create the request", e);
    }
      }

/**
 * Method to test getRequest Method.
 * @throws KMSClientException
 */
@Test
public void testGetRequest () throws KMSClientException
{
    try {
        final HttpResponse response = prepareResponse(HttpStatus.SC_OK);
        Mockito.when(httpClient.execute(Mockito.any())).thenReturn(response);
        final OrganizationResponse organizationResponse = kmsHttpClientImpl.invokeGETRequest
                (ORG_TEST_URL, OrganizationResponse.class);
        assertEquals("Id should match", ORG_ID, organizationResponse.getId());
    }  catch (IOException e) {
        throw new KMSClientException("Unable to create the request", e);
    }
}

/**
 * Method to organizationRequest Object.
 * @return OrganizationRequest object
 */
public OrganizationRequest getOrganizationRequest ()
{
    return OrganizationRequest.builder().id("test").build();
}

/**
 * Method to getOrganizationResponse String.
 * @return String Object
 */
public String getOrganizationResponse ()
{
    final Map obj=new HashMap();
    obj.put("id", ORG_ID);
    obj.put("uuid", ORG_UUID);
    obj.put("orgKeyId", ORG_KEYID);
    return JSONValue.toJSONString(obj);
}

/**
 * Method to prepare Response.
 * @param expectedResponseStatus
 * @return HttpResponse
 */
private HttpResponse prepareResponse (final int expectedResponseStatus)
{
    final HttpResponse response = new BasicHttpResponse(new BasicStatusLine(
            new ProtocolVersion("HTTP", 1, 1),
            expectedResponseStatus, ""));
    response.setStatusCode(expectedResponseStatus);
    final HttpEntity httpEntity = new StringEntity(getOrganizationResponse(),
            ContentType.APPLICATION_JSON);
    response.setEntity(httpEntity);
    return response;
     }
    }

Answer 1

测试 HTTP 客户端代码的方法之一是不模拟您的 HTTPClient 对象，而是为 http 调用创建模拟响应，然后让您的 HPPTClient 调用这些 URL。 看看 Wiremock。 http://wiremock.org/docs/ 它可以帮助您创建一个简单的模拟服务器，并且您可以为您的 URL 存根响应。 然后使用您的客户端调用您的 URL 进行测试。

Answer 2

在测试中使用模拟 HttpClient 的一种简单方法是添加第二个构造函数，该构造函数采用 HttpClient。

public class KMSHttpClientImpl implements KMSHttpClient
{

  private final HttpClient httpClient;

  public KMSHttpClientImpl ()
  {
    final PoolingHttpClientConnectionManager connectionManager =
            kmsHttpConnectionManager.getConnectionManager();
    httpClient = HttpClients.custom()
            .setConnectionManager(connectionManager)
            .build();
  }

  // This constructor is package private instead
  // of public so it is not accidentally used by
  // classes outside of this package. If your test
  // class is not in the same package, then you
  // need to make this a public constructor.
  KMSHttpClientImpl (final HttpClient httpClient)
  {
    this.httpClient = httpClient;
  }

}

然后，您使用此构造函数注入模拟的 HttpClient，并且在您的测试中既不需要 @InjectMocks 也不需要 @Mock。

@Test
public void testPostRequest () throws KMSClientException
{
  final HttpClient httpClient = Mockito.mock(HttpClient.class);
  final HttpResponse response = prepareResponse(HttpStatus.SC_OK);
  Mockito.when(httpClient.execute(Mockito.any())).thenReturn(response);
  final KMSHttpClientImpl kmsHttpClientImpl = new KMSHttpClientImpl(httpClient);

  // run your test...
}

Answer 3

您不能使用简单的模拟来模拟最终实例。你需要像PowerMock 这样的东西。

请参阅this question的答案以了解实施情况。