java - 对使用 httpclient 的类进行单元测试

Question

我想为这个使用HttpURLConnection的类编写单元测试用例。到目前为止我还没有使用过任何模拟框架，因此很难最终确定该方法。

public class DemoRestClient implements Closeable {

    private final String instanceId;
    private final String requestId;
    private HttpURLConnection conn;

    public DemoRestClient(String instance, String reqId, String url) {
        this.instanceId = instance;
        this.requestId = reqId;

        try {
            URL urlRequest = new URL(url);
            conn = (HttpURLConnection) urlRequest.openConnection();
        } catch (IOException iox) {
            throw new RuntimeException("Failed to connect", iox);
        }
    }

    public InputStream run() {

        try {
            conn.setRequestMethod("GET");
            conn.setRequestProperty("Accept", "application/json");
            conn.setRequestProperty("Accept-Encoding", "gzip");

            if (conn.getResponseCode() != 200) {
                throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
            }

            return new GZIPInputStream(conn.getInputStream());
        } catch (IOException iox) {
            throw new RuntimeException("Data fetching failed!", iox);
        }
    }

    @Override
    public void close() throws IOException {
        if (conn != null) {
            conn.disconnect();
        }
    }
}

如果您经历过这种情况，请遮挡一些光线。谢谢!

Answer 1

您必须在构造时提供 HttpURLConnection 或让 DemoRestClient 委托(delegate)给工厂(或类似工厂)来创建 HttpURLConnection。

例如:

public DemoRestClient(String instance, String reqId, HttpURLConnection connection) {
    ...
    this.conn = connection;
}

或者

public DemoRestClient(String instance, String reqId, ConnectionFactory connectionFactory) {
    ...
    this.conn = connectionFactory.create();
}

使用这两种方法中的任何一种，您都将控制 DemoRestService 中使用的实际 HttpURLConnection 实例，然后您可以开始模拟它以支持您所需的测试行为。

例如:

@Test
public void someTest() throws IOException {
    HttpURLConnection connection = Mockito.mock(HttpURLConnection.class);
    String instance = "...";
    String reqId = "...";

    DemoRestClient demoRestClient = new DemoRestClient(instance, reqId, connection);

    // in case you need to mock a response from the conneciton
    Mockito.when(connection.getInputStream()).thenReturn(...);

    demoRestClient.run();

    // in case you want to verify invocations on the connection
    Mockito.verify(connection).setRequestMethod("GET");
}