模拟类方法中的 NullPointerException

Question

我目前正在为 Buy 类的方法 buy 编写一个测试，它实际上应该测试正确的请求是否发送到服务器以及它是否正确处理了响应。

目前我总是收到 java.lang.NullPointerException，因为 execute(post) 返回 null 而不是 CloseableHttpResponse。

CloseableHttpResponse 响应 = httpClient.execute(post);

但我不明白，因为在我的测试中我告诉 mockito 返回模拟后的 closeableHttpResponse。

测试

  @Test
    public void testBid() throws IOException {
        //given:
        HttpPost post = mock(HttpPost.class);
        HttpResponse httpResponse = mock(HttpResponse.class);

        StatusLine statusLine = mock(StatusLine.class);

        ObserverImp observer = mock(ObserverImp.class);

        CloseableHttpClient closeableHttpClient = mock(CloseableHttpClient.class);
        CloseableHttpResponse closeableHttpResponse = mock(CloseableHttpResponse.class);
        HttpEntity httpEntity = mock(HttpEntity.class);
        BufferedInputStream inputStream = mock(BufferedInputStream.class);

        //and:
        when(statusLine.getStatusCode()).thenReturn(200);
        when(httpResponse.getStatusLine()).thenReturn(statusLine);
        when(closeableHttpClient.execute(post)).thenReturn(closeableHttpResponse);
        when(closeableHttpResponse.getEntity()).thenReturn(httpEntity);
        when(httpEntity.getContent()).thenReturn(inputStream);
        when(inputStream.read()).thenReturn(1);
        when(observer.getKey()).thenReturn("##213");


        Buy buy = new Buy(observer, closeableHttpClient);
        buy.bid(14455);
    }

以及相关的实现

public class Buy {
    private ObserverImp observer;
    private CloseableHttpClient httpClient;

    public Buy (ObserverImp observer, CloseableHttpClient httpClient) {
       this.observer = observer;
       this.httpClient = httpClient;
    }

    public void buy(double price) {
            String queryArgs = "command=order&amount=1" + "&price=" + String.valueOf(price); // generates query

            HttpPost post = new HttpPost("wwww.hm.edu/projectGroup1");
            post.addHeader("Key", observer.getKey());
            try {
                post.setEntity(new ByteArrayEntity(queryArgs.getBytes("UTF-8")));
            } catch (UnsupportedEncodingException e) {
                System.out.println("Exception in run");
            }
            List<NameValuePair> params = new ArrayList<>();

            params.add(new BasicNameValuePair("command", "order"));
            params.add(new BasicNameValuePair("amount", "1"));
            params.add(new BasicNameValuePair("price", String.valueOf(price)));
            try {
                post.setEntity(new UrlEncodedFormEntity(params));
                CloseableHttpResponse response = httpClient.execute(post);
                HttpEntity entity = response.getEntity();
                Scanner in = new Scanner(entity.getContent());
                String orderNumber = "";
                while (in.hasNext()) {
                    orderNumber = in.nextLine();
                }
                String[] findOrderNumber = orderNumber.split(".");
                long lastOrderNumber = -1;
                try {
                    lastOrderNumber = Long.valueOf(findOrderNumber[3]);
                } catch (NumberFormatException exception) {
                    System.out.println("NumberFormatException");
                } finally {
                    if (lastOrderNumber != -1) {
                        observer.setOrderNumber(lastOrderNumber);
                    }
                }
                in.close();
                EntityUtils.consume(entity);
                httpClient.close();
            } catch (IOException e) {
                System.out.println("Exception occured during process");
            }
        }
}

请帮我解决这个问题。非常感谢。

Answer 1

你需要那个：

when(closeableHttpClient.execute(any(HttpPost.class))).thenReturn(closeableHttpResponse);

您的代码之前只是等待您在测试中创建的确切帖子（等于）。但是您的购买方法会产生另一个帖子。这就是为什么您的 execute(post) 无法匹配班级的原因。 any() 解决了这个问题

Answer 2

需要设置返回类型，默认情况下mock会返回null。同样在实现中调用 createDefault http 对象。