java - 在非模拟方法中模拟方法

Question

我正在尝试模拟在另一个正在进行单元测试的方法中调用的方法。
但是，模拟无法正常工作，我收到了 UnknownHostException如果我从不首先 mock 内部方法，我就会得到。这可能是我的 throws 声明，因为我不知道该怎么做。任何帮助表示赞赏。

到目前为止，我的测试是这样的:

@Test
public void testServiceValidHost() throws ClientProtocolException, IOException {
    HealthService service = new HealthService();
    HealthService spy = Mockito.spy(service);

    when(spy.getHTTPResponse("http://" + HOST + "/health")).thenReturn(SOMESTATUS);

    String actual = spy. executeHealthCheck(HOST);
    assertEquals(SOMESTATUS, actual);
}

我测试的方法是 executeHealthCheck ，我想 mock getHTTPResponse

public String executeHealthCheck(String host) {
    try {
        String responseBody = getHTTPResponse("http://" + host + "/health");
        return responseBody;
    } catch (UnknownHostException e) {
        ...
        return "Invalid Host";
    } catch (Exception e) {
        ...
        return "Error";
    }
}

public String getHTTPResponse(String url) throws IOException, ClientProtocolException {
    CloseableHttpResponse response = null;
    HttpGet httpGet = new HttpGet(url);
    response = client.execute(httpGet);
    JSONObject responseBody = new JSONObject(EntityUtils.toString(response.getEntity()));
    return responseBody.toString();
}

Answer 1

考虑模拟该类并安排在 stub 所需成员的同时实际调用被测方法。

例如

@Test
public void testServiceValidHost() throws ClientProtocolException, IOException {
    //Arrange    
    HealthService service = Mockito.mock(HealthService.class);

    when(service.executeHealthCheck(HOST)).callRealMethod();
    when(service.getHTTPResponse("http://" + HOST + "/health")).thenReturn(SOMESTATUS);

    //Act
    String actual = service.executeHealthCheck(HOST);

    //Assert
    assertEquals(SOMESTATUS, actual);
}

但是根据文档，其中之一是 Important gotcha on spying real objects!

Sometimes it's impossible or impractical to use when(Object) for stubbing spies. Therefore when using spies please consider doReturn|Answer|Throw() family of methods for stubbing.

@Test
public void testServiceValidHost() throws ClientProtocolException, IOException {
    //Arrange
    HealthService service = new HealthService();
    HealthService spy = Mockito.spy(service);

    //You have to use doReturn() for stubbing
    doReturn(SOMESTATUS).when(spy).getHTTPResponse("http://" + HOST + "/health");

    //Act
    String actual = spy.executeHealthCheck(HOST);

    //Assert
    assertEquals(SOMESTATUS, actual);
}