Detailed explanation of Android unit testing and simulation testing

Testing and Basic Specifications

Why testing is needed?

For stability, we can clearly understand whether the development is completed correctly.

It is easier to maintain and can ensure that the function is not destroyed after modifying the code.

Integrate some tools to standardize development specifications and make the code more stable (such as submitting the unit tests that need to be executed when issuing a diff through phabricator differential, which can ensure the stability of the remote code in the development process).

2. What to test?

General unit testing:

List the exceptions you want to test and verify them.

Performance testing.

Simulation test: According to the needs, test the feedback and display of the interface during the actual use of the user, as well as the application testing of some components that depend on the system architecture.

3. It should be noted that

consider readability, use expressive method names for method names, and consider using a specification for test paradigms, such as RSpec-style. The method name can be in a format, such as: [Method of test]_[Condition of test]_[Expected result].

Don’t use logical flow keywords (If/else, for, do/while, switch/case). In a test method, if you need these, split them into each separate test method.

Test the content that really needs to be tested and the situations that need to be covered. Generally, only the verification output (such as what is displayed and what the value is after a certain operation) is considered.

Consider the time consumption, Android Studio will output the time consumption by default.

There is no need to consider testing private methods. Treat private methods as black box internal components and test the public methods referenced by them; do not consider testing trivial codes such as getters or setters.

Each unit test method should be in no order; decouple as much as possible. For different test methods, there should not be a situation where Test A and Test B have timing.

4. Create a test

Select the corresponding class

Place the cursor on the class name

Press ALT + ENTER

Select Create Test in the pop-up window

Unit testing in Android Studio and Simulation test

control + shift + R (Android Studio’s default execution unit test shortcut key).

1. Local unit testing

Run the test directly on the development machine.
Consider using this type of unit test only when there are no dependencies or only simple Android library dependencies are needed.

./gradlew check

(1) Code storage

If it corresponds to different flavors or build types, add the corresponding suffix directly after test (for example, the unit test code corresponding to myFlavor should be placed in src /testMyFlavor/java below).

src/test/java

(2)Google official recommended reference

dependencies {
    // Required -- JUnit 4 framework，用于单元测试，google官方推荐
    testCompile 'junit:junit:4.12'
    // Optional -- Mockito framework，用于模拟架构，google官方推荐
    //  http://www.manongjc.com/article/1546.html
    testCompile 'org.mockito:mockito-core:1.10.19'
}

(3)JUnit

Annotation

2. Simulation test

A test that needs to be run on an Android device or virtual machine.

Mainly used for testing: unit (unit testing related to Android SDK layer reference relationship), UI, application component integration testing (Service, Content Provider, etc.).

./gradlew connectedAndroidTest

(1) Code storage:

src/androidTest/java

(2) Google official recommendation

dependencies {
    androidTestCompile 'com.android.support:support-annotations:23.0.1'
    androidTestCompile 'com.android.support.test:runner:0.4.1'
    androidTestCompile 'com.android.support.test:rules:0.4.1'
    // Optional -- Hamcrest library
    androidTestCompile 'org.hamcrest:hamcrest-library:1.3'
    // Optional -- UI testing with Espresso
    //  http://www.manongjc.com/article/1546.html
    androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.1'
    // Optional -- UI testing with UI Automator
    androidTestCompile 'com.android.support.test.uiautomator:uiautomator-v18:2.1.1'
}

(3) Common UI tests

need to simulate the Android system environment.

Three main points:

Whether the information displayed after the UI is loaded is correct.

Whether the UI information is displayed correctly after a certain user operation.

Display the correct page for users to operate.

(4)Espresso

Google officially provides it for UI interaction testing

import static android.support.test.espresso.Espresso.onView;
import static android.support.test.espresso.action.ViewActions.click;
import static android.support.test.espresso.assertion.ViewAssertions.matches;
import static android.support.test.espresso.matcher.ViewMatchers.isDisplayed;
import static android.support.test.espresso.matcher.ViewMatchers.withId;

// 对于Id为R.id.my_view的View: 触发点击，检测是否显示
onView(withId(R.id.my_view)).perform(click())               
                            .check(matches(isDisplayed()));
// 对于文本打头是"ABC"的View: 检测是否没有Enable
onView(withText(startsWith("ABC"))).check(matches(not(isEnabled()));
// 按返回键
pressBack();
// 对于Id为R.id.button的View: 检测内容是否是"Start new activity"
// http://www.manongjc.com/article/1537.html
onView(withId(R.id.button)).check(matches(withText(("Start new activity"))));
// 对于Id为R.id.viewId的View: 检测内容是否不包含"YYZZ"
onView(withId(R.id.viewId)).check(matches(withText(not(containsString("YYZZ")))));
// 对于Id为R.id.inputField的View: 输入"NewText"，然后关闭软键盘
onView(withId(R.id.inputField)).perform(typeText("NewText"), closeSoftKeyboard());
// 对于Id为R.id.inputField的View: 清除内容
onView(withId(R.id.inputField)).perform(clearText());

Start an Intent that opens the Activity

@RunWith(AndroidJUnit4.class)
public class SecondActivityTest {
    @Rule
    public ActivityTestRule<SecondActivity> rule =
            new ActivityTestRule(SecondActivity.class, true,
                                  // 这个参数为false，不让SecondActivity自动启动
                                  // 如果为true，将会在所有@Before之前启动，在最后一个@After之后关闭
                                  false);
    @Test
    public void demonstrateIntentPrep() {
        Intent intent = new Intent();
        intent.putExtra("EXTRA", "Test");
        // 启动SecondActivity并传入intent
        rule.launchActivity(intent);
        // 对于Id为R.id.display的View: 检测内容是否是"Text"
        // http://www.manongjc.com/article/1532.html
        onView(withId(R.id.display)).check(matches(withText("Test")));
    }
}

(5) Asynchronous interaction

It is recommended to turn off the animation in "Settings->Developer Options" in the device , because these animations may confuse Espresso when detecting asynchronous tasks: Window animation scale, Transition animation scale, Animator duration scale.

For AsyncTask, during testing, if an AsyncTask task is thrown after a click event is triggered, directly onView(withId(R.id.update)).perform(click()) during testing, and then directly detect it. The detection at this time is after AsyncTask#onPostExecute.

// 通过实现IdlingResource，block住当非空闲的时候，当空闲时进行检测，非空闲的这段时间处理异步事情
public class IntentServiceIdlingResource implements IdlingResource {
    ResourceCallback resourceCallback;
    private Context context;

    public IntentServiceIdlingResource(Context context) { this.context = context; }

    @Override public String getName() { return IntentServiceIdlingResource.class.getName(); }

    @Override public void registerIdleTransitionCallback( ResourceCallback resourceCallback) { this.resourceCallback = resourceCallback; }

    @Override public boolean isIdleNow() {
      // 是否是空闲
      // 如果IntentService 没有在运行，就说明异步任务结束，IntentService特质就是启动以后处理完Intent中的事务，理解关闭自己
      // http://www.manongjc.com/article/1531.html
        boolean idle = !isIntentServiceRunning();
        if (idle && resourceCallback != null) {
          // 回调告知异步任务结束
            resourceCallback.onTransitionToIdle();
        }
        return idle;
    }

    private boolean isIntentServiceRunning() {
        ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        // Get all running services
        List<ActivityManager.RunningServiceInfo> runningServices = manager.getRunningServices(Integer.MAX_VALUE);
        // check if our is running
        for (ActivityManager.RunningServiceInfo info : runningServices) {
            if (MyIntentService.class.getName().equals(info.service.getClassName())) {
                return true;
            }
        }
        return false;
    }
}

// 使用IntentServiceIdlingResource来测试，MyIntentService服务启动结束这个异步事务，之后的结果。
@RunWith(AndroidJUnit4.class)
public class IntegrationTest {

    @Rule
    public ActivityTestRule rule = new ActivityTestRule(MainActivity.class);
    IntentServiceIdlingResource idlingResource;

    @Before
    public void before() {
        Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
        Context ctx = instrumentation.getTargetContext();
        idlingResource = new IntentServiceIdlingResource(ctx);
        // 注册这个异步监听
        Espresso.registerIdlingResources(idlingResource);

    }
    @After
    public void after() {
        // 取消注册这个异步监听
        Espresso.unregisterIdlingResources(idlingResource);

    }

    @Test
    public void runSequence() {
        // MainActivity中点击R.id.action_settings这个View的时候，会启动MyIntentService
        onView(withId(R.id.action_settings)).perform(click());
        // 这时候IntentServiceIdlingResource#isIdleNow会返回false，因为MyIntentService服务启动了
        // 这个情况下，这里会block住.............
        // 直到IntentServiceIdlingResource#isIdleNow返回true，并且回调了IntentServiceIdlingResource#onTransitionToIdle
        // 这个情况下，继续执行，这时我们就可以测试异步结束以后的情况了。
        onView(withText("Broadcast")).check(matches(notNullValue()));
    }
}

(6) Custom matcher

// 定义
public static Matcher<View> withItemHint(String itemHintText) {
  checkArgument(!(itemHintText.equals(null)));
  return withItemHint(is(itemHintText));
}

public static Matcher<View> withItemHint(final Matcher<String> matcherText) {
  checkNotNull(matcherText);
  return new BoundedMatcher<View, EditText>(EditText.class) {

    @Override
    public void describeTo(Description description) {
      description.appendText("with item hint: " + matcherText);
    }

    @Override
    protected boolean matchesSafely(EditText editTextField) {
      // 取出hint，然后比对下是否相同
      // http://www.manongjc.com/article/1524.html
      return matcherText.matches(editTextField.getHint().toString());
    }
  };
}

// 使用
onView(withItemHint("test")).check(matches(isDisplayed()));

拓展工具

1. AssertJ Android

square/assertj-android
极大的提高可读性。

import static org.assertj.core.api.Assertions.*;

// 断言: view是GONE的
assertThat(view).isGone();

MyClass test = new MyClass("Frodo");
MyClass test1 = new MyClass("Sauron");
MyClass test2 = new MyClass("Jacks");

List<MyClass> testList = new ArrayList<>();
testList.add(test);
testList.add(test1);

// 断言: test.getName()等于"Frodo"
assertThat(test.getName()).isEqualTo("Frodo");
// 断言: test不等于test1并且在testList中
// http://www.manongjc.com/article/1519.html
assertThat(test).isNotEqualTo(test1)
                 .isIn(testList);
// 断言: test.getName()的字符串，是由"Fro"打头，以"do"结尾，忽略大小写会等于"frodo"
assertThat(test.getName()).startsWith("Fro")
                            .endsWith("do")
                            .isEqualToIgnoringCase("frodo");
// 断言: testList有2个数据，包含test，test1，不包含test2
assertThat(list).hasSize(2)
                .contains(test, test1)
                .doesNotContain(test2);

// 断言: 提取testList队列中所有数据中的成员变量名为name的变量，并且包含name为"Frodo"与"Sauron"
//      并且不包含name为"Jacks"
assertThat(testList).extracting("name")
                    .contains("Frodo", "Sauron")
                    .doesNotContain("Jacks");

2. Hamcrest

JavaHamcrest
通过已有的通配方法，快速的对代码条件进行测试
org.hamcrest:hamcrest-junit:(version)

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.Matchers.equalTo;

// 断言: a等于b
assertThat(a, equalTo(b));
assertThat(a, is(equalTo(b)));
assertThat(a, is(b));
// 断言: a不等于b
assertThat(actual, is(not(equalTo(b))));

List<Integer> list = Arrays.asList(5, 2, 4);
// 断言: list有3个数据
assertThat(list, hasSize(3));
// 断言: list中有5,2,4，并且顺序也一致
assertThat(list, contains(5, 2, 4));
// 断言: list中包含5,2,4
assertThat(list, containsInAnyOrder(2, 4, 5));
// 断言: list中的每一个数据都大于1
// http://www.manongjc.com/article/1507.html
assertThat(list, everyItem(greaterThan(1)));
// 断言: fellowship中包含有成员变量"race"，并且其值不是ORC
assertThat(fellowship, everyItem(hasProperty("race", is(not((ORC))))));
// 断言: object1中与object2相同的成员变量都是相同的值
assertThat(object1, samePropertyValuesAs(object2));

Integer[] ints = new Integer[] { 7, 5, 12, 16 };
// 断言: 数组中包含7,5,12,16
assertThat(ints, arrayContaining(7, 5, 12, 16));

(1)几个主要的匹配器:

(2)自定义匹配器

// 自定义
import org.hamcrest.Description;
import org.hamcrest.TypeSafeMatcher;

public class RegexMatcher extends TypeSafeMatcher<String> {
    private final String regex;

    public RegexMatcher(final String regex) { this.regex = regex; }
    @Override
    public void describeTo(final Description description) { description.appendText("matches regular expression=`" + regex + "`"); }

    @Override
    public boolean matchesSafely(final String string) { return string.matches(regex); }

    // 上层调用的入口
    public static RegexMatcher matchesRegex(final String regex) {
        return new RegexMatcher(regex);
    }
}

// 使用
String s = "aaabbbaaa";
assertThat(s, RegexMatcher.matchesRegex("a*b*a"));

3. Mockito

Mockito
Mock对象，控制其返回值，监控其方法的调用。
org.mockito:mockito-all:(version)

// import如相关类
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.verify;

// 创建一个Mock的对象
 MyClass test = mock(MyClass.class);

// 当调用test.getUniqueId()的时候返回43
when(test.getUniqueId()).thenReturn(43);
// 当调用test.compareTo()传入任意的Int值都返回43
when(test.compareTo(anyInt())).thenReturn(43);
// 当调用test.compareTo()传入的是Target.class类型对象时返回43
when(test.compareTo(isA(Target.class))).thenReturn(43);
// 当调用test.close()的时候，抛IOException异常
doThrow(new IOException()).when(test).close();
// 当调用test.execute()的时候，什么都不做
doNothing().when(test).execute();

// 验证是否调用了两次test.getUniqueId()
// http://www.manongjc.com/article/1503.html
verify(test, times(2)).getUniqueId();
// 验证是否没有调用过test.getUniqueId()
verify(test, never()).getUniqueId();
// 验证是否至少调用过两次test.getUniqueId()
verify(test, atLeast(2)).getUniqueId();
// 验证是否最多调用过三次test.getUniqueId()
verify(test, atMost(3)).getUniqueId();
// 验证是否这样调用过:test.query("test string")
verify(test).query("test string");

// 通过Mockito.spy() 封装List对象并返回将其mock的spy对象
List list = new LinkedList();
List spy = spy(list);

// 指定spy.get(0)返回"foo"
doReturn("foo").when(spy).get(0);

assertEquals("foo", spy.get(0));

对访问方法时，传入参数进行快照

import org.mockito.ArgumentCaptor;
import org.mockito.Captor;
import static org.junit.Assert.assertEquals;

@Captor
private ArgumentCaptor<Integer> captor;

@Test
public void testCapture(){
  MyClass test = mock(MyClass.class);

  test.compareTo(3, 4);
  verify(test).compareTo(captor.capture(), eq(4));

  assertEquals(3, (int)captor.getValue());

  // 需要特别注意，如果是可变数组(vargars)参数，如方法 test.doSomething(String... params)
  // 此时是使用ArgumentCaptor<String>，而非ArgumentCaptor<String[]>
  ArgumentCaptor<String> varArgs = ArgumentCaptor.forClass(String.class);
  test.doSomething("param-1", "param-2");
  verify(test).doSomething(varArgs.capture());

  // 这里直接使用getAllValues()而非getValue()，来获取可变数组参数的所有传入参数
  assertThat(varArgs.getAllValues()).contains("param-1", "param-2");
}

(1)对于静态的方法的Mock:

可以使用 PowerMock:

org.powermock:powermock-api-mockito:(version) & org.powermock:powermock-module-junit4:(version)(For PowerMockRunner.class)

@RunWith(PowerMockRunner.class)
@PrepareForTest({StaticClass1.class, StaticClass2.class})
public class MyTest {

  @Test
  public void testSomething() {
    // mock完静态类以后，默认所有的方法都不做任何事情
    mockStatic(StaticClass1.class);
    when(StaticClass1.getStaticMethod()).andReturn("anything");

    // 验证是否StaticClass1.getStaticMethod()这个方法被调用了一次
    verifyStatic(time(1));
    StaticClass1.getStaticMethod();

    when(StaticClass1.getStaticMethod()).andReturn("what ever");

    // 验证是否StaticClass2.getStaticMethod()这个方法被至少调用了一次
    verifyStatic(atLeastOnce());
    StaticClass2.getStaticMethod();

    // 通过任何参数创建File的实力，都直接返回fileInstance对象
    whenNew(File.class).withAnyArguments().thenReturn(fileInstance);
  }
}

或者是封装为非静态，然后用Mockito:

class FooWraper{  void someMethod() {
    Foo.someStaticMethod();
  }
}

4. Robolectric

Robolectric
让模拟测试直接在开发机上完成，而不需要在Android系统上。所有需要使用到系统架构库的，如(Handler、HandlerThread)都需要使用Robolectric，或者进行模拟测试。

主要是解决模拟测试中耗时的缺陷，模拟测试需要安装以及跑在Android系统上，也就是需要在Android虚拟机或者设备上面，所以十分的耗时。基本上每次来来回回都需要几分钟时间。针对这类问题，业界其实已经有了一个现成的解决方案: Pivotal实验室推出的Robolectric。通过使用Robolectrict模拟Android系统核心库的Shadow Classes的方式，我们可以像写本地测试一样写这类测试，并且直接运行在工作环境的JVM上，十分方便。

 

5. Robotium

RobotiumTech/robotium
(Integration Tests)模拟用户操作，事件流测试。

@RunWith(RobolectricTestRunner.class)
@Config(constants = BuildConfig.class)
public class MyActivityTest{

@Test
  public void doSomethingTests(){
    // 获取Application对象
    Application application = RuntimeEnvironment.application;

    // 启动WelcomeActivity
    WelcomeActivity activity = Robolectric.setupActivity(WelcomeActivity.class);
    // 触发activity中Id为R.id.login的View的click事件
    // http://www.manongjc.com/article/1502.html
    activity.findViewById(R.id.login).performClick();

    Intent expectedIntent = new Intent(activity, LoginActivity.class);
    // 在activity之后，启动的Activity是否是LoginActivity
    assertThat(shadowOf(activity).getNextStartedActivity()).isEqualTo(expectedIntent);
  }
}

通过模拟用户的操作的行为事件流进行测试，这类测试无法避免需要在虚拟机或者设备上面运行的。是一些用户操作流程与视觉显示强相关的很好的选择。

 

6. Test Butler

linkedin/test-butler
避免设备/模拟器系统或者环境的错误，导致测试的失败。

通常我们在进行UI测试的时候，会遇到由于模拟器或者设备的错误，如系统的crash、ANR、或是未预期的Wifi、CPU罢工，或者是锁屏，这些外再环境因素导致测试不过。Test-Butler引入就是避免这些环境因素导致UI测试不过。

该库被谷歌官方推荐过，并且收到谷歌工程师的Review。

 

拓展思路

1. Android Robots

Instrumentation Testing Robots – Jake Wharton

假如我们需要测试: 发送 $42 到 “foo@bar.com”，然后验证是否成功。

(1)通常的做法

(2)Robot思想

在写真正的UI测试的时候，只需要关注要测试什么，而不需要关注需要怎么测试，换句话说就是让测试逻辑与View或Presenter解耦，而与数据产生关系。

首先通过封装一个Robot去处理How的部分:

然后在写测试的时候，只关注需要测试什么:

终的思想原理