如何在spock框架中模拟HttpURLConnection及其responseCode

Question

我正在使用Java并使用groovy中的spock框架编写junit，想要模拟HttpUrlConnection并设置connection.getResponseCode()>> 200 根据不同情况。

URL url = new URL(proxySettingDTO.getTestUrl());
HttpURLConnection connection = (HttpURLConnection) url.openConnection(proxy);
connection.setRequestMethod("GET");
connection.setUseCaches(false);
...
LOGGER.debug("Response code ::{} ",connection.getResponseCode()); //200 or 403

我尝试过使用

HttpURLConnection httpURLConnection = Mock()
URL url = new URL(proxySettingDTO.getTestUrl());
url.openConnection(_) >> httpURLConnection

但它不起作用。

Answer 1

您的问题有几个问题：

1. In url.openConnection(_) >>> httpURLConnection 您正在尝试存根方法结果，但您的 URL 对象未声明为模拟、存根或间谍。也就是说，你的尝试注定会失败。

2. 即使您尝试模拟 URL，该 JDK 类也是最终的，即您无法模拟它，因为模拟是子类。

3. 被测试的类通过调用url.openConnection(proxy)来获取HttpURLConnection。由于 (3)，该方法不可模拟，因此您应该将连接创建外部化到辅助类 ConnectionManager 中，然后将模拟实例注入到被测试的类中，以使其可测试。

一般来说，测试是一种设计工具，而不仅仅是用测试来覆盖代码。如果测试很困难，则意味着组件设计耦合得太紧。让测试帮助使用 TDD（测试驱动开发）或至少测试驱动重构来驱动您的设计，即使后者有点晚了并且意味着返工。如果您对组件进行更多的解耦，例如不创建您的类在内部依赖的对象实例，而是允许 API 用户注入它们（例如通过构造函数或 setter），那么可测试性会更好，并且您的头痛也会减少。

这个怎么样？

class UnderTest {
  private Proxy proxy
  private ProxySettingDTO proxySettingDTO
  private ConnectionManager connectionManager
   UnderTest(Proxy proxy, ProxySettingDTO proxySettingDTO, ConnectionManager connectionManager) {
    this.proxy = proxy
    this.proxySettingDTO = proxySettingDTO
    this.connectionManager = connectionManager
  }

  int getConnectionResponseCode() {
    URL url = new URL(proxySettingDTO.getTestUrl())
    HttpURLConnection connection = (HttpURLConnection) connectionManager.openConnection(url, proxy)
    connection.setRequestMethod("GET")
    connection.setUseCaches(false)
    connection.getResponseCode()
  }
}

class ProxySettingDTO {
  String getTestUrl() {
    "https://scrum-master.de"
  }
}

class ConnectionManager {
  URLConnection openConnection(URL url, Proxy proxy) {
    url.openConnection(proxy)
  }
}

package de.scrum_master.stackoverflow.q71616286

import spock.lang.Specification

class HttpConnectionMockTest extends Specification {
  def test() {
    given: "a mock connection manager, returning a mock connection with a predefined response code"
    ConnectionManager connectionManager = Mock() {
      openConnection(_, _) >> Mock(HttpURLConnection) {
        getResponseCode() >> 200
      }
    }

    and: "an object under test using mock proxy, real DTO and mock connection manager"
    def underTest = new UnderTest(Mock(Proxy), new ProxySettingDTO(), connectionManager)

    expect: "method under test returns expected response"
    underTest.getConnectionResponseCode() == 200
  }
}

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