MockWebServer 示例

如果你的活动，片段和 UI 需要一些后台处理，那么使用的好东西是 MockWebServer，它在 Android 设备上运行 localy，为你的 UI 带来封闭且可测试的环境。

https://github.com/square/okhttp/tree/master/mockwebserver

第一步是包括 gradle 依赖：

testCompile 'com.squareup.okhttp3:mockwebserver:(insert latest version)'

现在运行和使用模拟服务器的步骤是：

• 创建模拟服务器对象
• 在特定地址和端口启动它（通常是 localhost：portnumber）
• 将特定请求的响应排入队列
• 开始测试

在 mockwebserver 的 github 页面中很好地解释了这一点，但在我们的例子中，我们希望所有测试都有更好的和可重用的东西，JUnit 规则将在这里很好地发挥作用：

/**
 *JUnit  rule that starts and stops a mock web server for test runner
*/
 public class MockServerRule extends UiThreadTestRule {

 private MockWebServer mServer;

 public static final int MOCK_WEBSERVER_PORT = 8000;

    @Override
    public Statement apply(final Statement base, Description description) {
        return new Statement() {
            @Override
            public void evaluate() throws Throwable {
                startServer();
                try {
                    base.evaluate();
                } finally {
                    stopServer();
                }
            }
        };
    }

    /**
     * Returns the started web server instance
     *
     * @return mock server
     */
    public MockWebServer server() {
        return mServer;
    }

    public void startServer() throws IOException, NoSuchAlgorithmException {
        mServer = new MockWebServer();
        try {
            mServer(MOCK_WEBSERVER_PORT);
        } catch (IOException e) {
            throw new IllegalStateException(e,"mock server start issue");
        }
    }

    public void stopServer() {
        try {
            mServer.shutdown();
        } catch (IOException e) {
            Timber.e(e, "mock server shutdown error”);
        }
    }
}

现在让我们假设我们拥有与之前示例完全相同的活动，就在这种情况下，当我们按下按钮时，应用程序将从网络中获取某些内容，例如： https ： //someapi.com/name

这将返回一些文本字符串，这些文本字符串将在快餐栏文本中连接，例如你键入的 NAME +文本。

/**
* Testing of the snackbar activity with networking.
**/
@RunWith(AndroidJUnit4.class)
@LargeTest
public class SnackbarActivityTest{
    //espresso rule which tells which activity to start
    @Rule
    public final ActivityTestRule<SnackbarActivity> mActivityRule = 
        new ActivityTestRule<>(SnackbarActivity.class, true, false);

    //start mock web server
    @Rule
    public final MockServerRule mMockServerRule = new MockServerRule();

    @Override
    public void tearDown() throws Exception {
       //same as previous example
    }
    
    @Override
    public void setUp() throws Exception {
       //same as previous example

       **//IMPORTANT:** point your application to your mockwebserver endpoint e.g.
       MyAppConfig.setEndpointURL("http://localhost:8000");
    }
    
    /**
    *Test methods should always start with "testXYZ" and it is a good idea to 
    *name them after the intent what you want to test
    **/
    @Test
    public void testSnackbarIsShown() {
        //setup mockweb server
        mMockServerRule.server().setDispatcher(getDispatcher());

        mActivityRule.launchActivity(null);
        //check is our text entry displayed and enter some text to it
        String textToType="new snackbar text";
        onView(withId(R.id.textEntry)).check(matches(isDisplayed()));
        //we check is our snackbar showing text from mock webserver plus the one we typed
        onView(withId(R.id.textEntry)).perform(typeText("JazzJackTheRabbit" + textToType));
        //click the button to show the snackbar
        onView(withId(R.id.shownSnackbarBtn)).perform(click());
        //assert that a view with snackbar_id with text which we typed and is displayed
        onView(allOf(withId(android.support.design.R.id.snackbar_text), 
        withText(textToType))) .check(matches(isDisplayed()));
    }
    
     /**
     *creates a mock web server dispatcher with prerecorded requests and responses
     **/
    private Dispatcher getDispatcher() {
        final Dispatcher dispatcher = new Dispatcher() {
            @Override
            public MockResponse dispatch(RecordedRequest request) throws InterruptedException {
                if (request.getPath().equals("/name")){
                    return new MockResponse().setResponseCode(200)
                            .setBody("JazzJackTheRabbit");
                }
                throw new IllegalStateException("no mock set up for " + request.getPath());
            }
        };
        return dispatcher;
    }

我建议将调度程序包装在某种类型的 Builder 中，这样你就可以轻松地为你的屏幕链接并添加新的响应。例如

 return newDispatcherBuilder()
            .withSerializedJSONBody("/authenticate", Mocks.getAuthenticationResponse())
            .withSerializedJSONBody("/getUserInfo", Mocks.getUserInfo())
            .withSerializedJSONBody("/checkNotBot", Mocks.checkNotBot());