android - 使用 Android volley 进行单元测试

Question

我想知道如何为 volley 框架创建单元测试。模拟请求和响应，以便我可以创建不需要 Web 服务工作和网络访问的单元测试。

我用谷歌搜索了它，但我根本没有找到关于框架的太多信息

Answer 1

我实现了一个名为FakeHttpStack的HttpStack子类，它从位于 res/raw 的本地文件中加载假响应体。我这样做是为了开发目的，也就是说，我可以在服务器准备好之前为新的 API 开发一些东西，但是你可以从这里学到一些东西（例如，覆盖 HttpStack#peformRequest 和 createEntity）。

/**
 * Fake {@link HttpStack} that returns the fake content using resource file in res/raw.
 */
class FakeHttpStack implements HttpStack {
    private static final String DEFAULT_STRING_RESPONSE = "Hello";
    private static final String DEFAULT_JSON_RESPONSE = " {\"a\":1,\"b\":2,\"c\":3}";
    private static final String URL_PREFIX = "http://example.com/";
    private static final String LOGGER_TAG = "STACK_OVER_FLOW";

    private static final int SIMULATED_DELAY_MS = 500;
    private final Context context;

    FakeHttpStack(Context context) {
        this.context = context;
    }

    @Override
    public HttpResponse performRequest(Request<?> request, Map<String, String> stringStringMap)
            throws IOException, AuthFailureError {
        try {
            Thread.sleep(SIMULATED_DELAY_MS);
        } catch (InterruptedException e) {
        }
        HttpResponse response
                = new BasicHttpResponse(new BasicStatusLine(HttpVersion.HTTP_1_1, 200, "OK"));
        List<Header> headers = defaultHeaders();
        response.setHeaders(headers.toArray(new Header[0]));
        response.setLocale(Locale.JAPAN);
        response.setEntity(createEntity(request));
        return response;
    }

    private List<Header> defaultHeaders() {
        DateFormat dateFormat = new SimpleDateFormat("EEE, dd mmm yyyy HH:mm:ss zzz");
        return Lists.<Header>newArrayList(
                new BasicHeader("Date", dateFormat.format(new Date())),
                new BasicHeader("Server",
                        /* Data below is header info of my server */
                        "Apache/1.3.42 (Unix) mod_ssl/2.8.31 OpenSSL/0.9.8e")
        );
    }

    /**
     * returns the fake content using resource file in res/raw. fake_res_foo.txt is used for
     * request to http://example.com/foo
     */
    private HttpEntity createEntity(Request request) throws UnsupportedEncodingException {
        String resourceName = constructFakeResponseFileName(request);
        int resourceId = context.getResources().getIdentifier(
                resourceName, "raw", context.getApplicationContext().getPackageName());
        if (resourceId == 0) {
            Log.w(LOGGER_TAG, "No fake file named " + resourceName
                    + " found. default fake response should be used.");
        } else {
            InputStream stream = context.getResources().openRawResource(resourceId);
            try {
                String string = CharStreams.toString(new InputStreamReader(stream, Charsets.UTF_8));
                return new StringEntity(string);
            } catch (IOException e) {
                Log.e(LOGGER_TAG, "error reading " + resourceName, e);
            }
        }

        // Return default value since no fake file exists for given URL.
        if (request instanceof StringRequest) {
            return new StringEntity(DEFAULT_STRING_RESPONSE);
        }
        return new StringEntity(DEFAULT_JSON_RESPONSE);
    }

    /**
     * Map request URL to fake file name
     */
    private String constructFakeResponseFileName(Request request) {
        String reqUrl = request.getUrl();
        String apiName = reqUrl.substring(URL_PREFIX.length());
        return "fake_res_" + apiName;
    }
}

要使用 FakeHttpStack，您只需将它传递给您的RequestQueue。我也覆盖了 RequestQueue。

public class FakeRequestQueue extends RequestQueue {
    public FakeRequestQueue(Context context) {
        super(new NoCache(), new BasicNetwork(new FakeHttpStack(context)));
    }
}

这种方法的好处是，它不需要对您的代码进行太多更改。您只需在测试时将RequestQueue切换为FakeRequestQueue。因此，它可以用于验收测试或系统测试。

另一方面，对于单元测试，可能有更紧凑的方式。例如，您可以将Request.Listener子类实现为单独的类，以便可以轻松测试 onResponse 方法。我建议您提供有关要测试的内容的更多详细信息或放置一些代码片段。

Answer 2

查看 volley tests文件夹，您可以在其中找到示例。

MockCache.java
MockHttpClient.java
MockHttpStack.java
MockHttpURLConnection.java
MockNetwork.java
MockRequest.java
MockResponseDelivery.java

Answer 3

不是 100% 确定我理解你想要做什么，但如果我理解了，那么 easymock（一个允许创建模拟类的库，你可以调用并接收预定的响应）会帮助你很多。一个叫 Lars Vogel 的人有一篇关于这个主题的不错的文章，我在不久前使用它时发现它很有用。

http://www.vogella.com/articles/EasyMock/article.html

Answer 4

这是@Dmytro 提到的当前 volley 的 MockHttpStack的副本

package com.android.volley.mock;
import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.toolbox.HttpStack;
import org.apache.http.HttpResponse;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
public class MockHttpStack implements HttpStack {
    private HttpResponse mResponseToReturn;
    private IOException mExceptionToThrow;
    private String mLastUrl;
    private Map<String, String> mLastHeaders;
    private byte[] mLastPostBody;
    public String getLastUrl() {
        return mLastUrl;
    }
    public Map<String, String> getLastHeaders() {
        return mLastHeaders;
    }
    public byte[] getLastPostBody() {
        return mLastPostBody;
    }
    public void setResponseToReturn(HttpResponse response) {
        mResponseToReturn = response;
    }
    public void setExceptionToThrow(IOException exception) {
        mExceptionToThrow = exception;
    }
    @Override
    public HttpResponse performRequest(Request<?> request, Map<String, String> additionalHeaders)
            throws IOException, AuthFailureError {
        if (mExceptionToThrow != null) {
            throw mExceptionToThrow;
        }
        mLastUrl = request.getUrl();
        mLastHeaders = new HashMap<String, String>();
        if (request.getHeaders() != null) {
            mLastHeaders.putAll(request.getHeaders());
        }
        if (additionalHeaders != null) {
            mLastHeaders.putAll(additionalHeaders);
        }
        try {
            mLastPostBody = request.getBody();
        } catch (AuthFailureError e) {
            mLastPostBody = null;
        }
        return mResponseToReturn;
    }
}