Espresso ui单元测试框架初探

Espresso是google出的一款UI单元测试的框架。
首先配置下gradle:
defaultConfig中配置testImstrumentationRunner:

testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

dependencies里面配置如下：

dependencies {    compile fileTree(dir: 'libs', include: ['*.jar'])    testCompile 'junit:junit:4.12'    compile 'com.android.support:appcompat-v7:23.0.1'    androidTestCompile 'com.android.support.test:runner:0.4'    androidTestCompile 'com.android.support.test:rules:0.4'    androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.1'    androidTestCompile 'com.android.support.test.uiautomator:uiautomator-v18:2.1.2'}

build variants需要配置成 Android Instrumentation Tests模式：

先来看看ui测试布局activity_main.xml：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"              android:layout_width="match_parent"              android:layout_height="match_parent"              android:orientation="vertical">    <Button        android:id="@+id/button"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:onClick="sayHello"        android:text="button test!"/>    <EditText        android:id="@+id/edittext"        android:layout_width="match_parent"        android:layout_height="wrap_content"/>    <TextView        android:id="@+id/textview"        android:layout_width="match_parent"        android:layout_height="match_parent"/></LinearLayout>

MainActivity中注册click点击事件：

    public void sayHello(View view) {        mTextView = (TextView) findViewById(R.id.textview);        mEditText = (EditText) findViewById(R.id.edittext);        mTextView.setText("Hello, " + mEditText.getText().toString() + "!");    }

这里我们在androidTest包下面建立相关单元测试类MainActivityInstrumentationTest:

package com.example.hongentao.junitdemo;import android.support.test.rule.ActivityTestRule;import android.support.test.runner.AndroidJUnit4;import android.test.suitebuilder.annotation.LargeTest;import org.junit.Rule;import org.junit.Test;import org.junit.runner.RunWith;import static android.support.test.espresso.Espresso.onView;import static android.support.test.espresso.action.ViewActions.click;import static android.support.test.espresso.action.ViewActions.closeSoftKeyboard;import static android.support.test.espresso.action.ViewActions.typeText;import static android.support.test.espresso.assertion.ViewAssertions.matches;import static android.support.test.espresso.matcher.ViewMatchers.withId;import static android.support.test.espresso.matcher.ViewMatchers.withText;@RunWith(AndroidJUnit4.class)@LargeTest/** * Created by hongentao on 16/2/26. */public class MainActivityInstrumentationTest {    private static final String STRING_TO_BE_TYPED = "Peter is greate!!! we will be fine! and something will be ok!";    @Rule    public ActivityTestRule<MainActivity> mActivityRule = new ActivityTestRule<>(            MainActivity.class);    @Test    public void OnclickJunitTest() {        onView(withId(R.id.edittext)).perform(typeText(STRING_TO_BE_TYPED), closeSoftKeyboard()); //line 1        onView(withId(R.id.button)).perform(click()); //line 2        String expectedText = "Hello, " + STRING_TO_BE_TYPED + "!";        onView(withId(R.id.textview)).check(matches(withText(expectedText))); //line 3    }}

楼上注解的含义：

@Test: 标识一个测试方法。一个测试类中可以有多个测试方法，每个测试方法需要用一个@Test注解来标识。

@Rule: 简单来说，是为各个测试方法提供一些支持。具体来说，比如我需要测试一个Activity，那么我可以在@Rule注解下面采用一个ActivityTestRule，该类提供了对相应Activity的功能测试的支持。该类可以在@Before和@Test标识的方法执行之前确保将Activity运行起来，并且在所有@Test和@After方法执行结束之后将Activity杀死。在整个测试期间，每个测试方法都可以直接对相应Activity进行修改和访问。

我们来分析下OnclickJunitTest()方法具体的含义：

    @Test    public void OnclickJunitTest() {        onView(withId(R.id.edittext)).perform(typeText(STRING_TO_BE_TYPED), closeSoftKeyboard()); //line 1        onView(withId(R.id.button)).perform(click()); //line 2        String expectedText = "Hello, " + STRING_TO_BE_TYPED + "!";        onView(withId(R.id.textview)).check(matches(withText(expectedText))); //line 3    }

line1代码讲解：
onView(withId(R.id.edittext))—>找到id为editText的View.
perform(typeText(text), closeSoftKeyboard)—>我们来看下源码：

/**   * Performs the given action(s) on the view selected by the current view matcher. If more than one   * action is provided, actions are executed in the order provided with precondition checks running   * prior to each action.   *   * @param viewActions one or more actions to execute.   * @return this interaction for further perform/verification calls.   */  public ViewInteraction perform(final ViewAction... viewActions) {    checkNotNull(viewActions);    for (ViewAction action : viewActions) {      doPerform(action);    }    return this;  }

根据注释大概可以看出：根据当前被匹配的View,按照相应的ViewAction按照顺序依次执行。
所以上面 perform(typeText(text), closeSoftKeyboard)的含义为：将text值赋给editText（typeText是将赋值行为转为viewAction），然后关闭closeSoftKeyboard。
看下closeSoftKeyboard的源码：

 }  /**   * Returns an action that closes soft keyboard. If the keyboard is already closed, it is a no-op.   */  public static ViewAction closeSoftKeyboard() {    return actionWithAssertions(new CloseKeyboardAction());  }

通过注释以及返回值一目了然：
line2代码讲解：
onView(withId(R.id.button)).perform(click())—找到id为button的按钮，执行click点击事件：

line3代码讲解：
onView(withId(R.id.textview)).check(matches(withText(expectedText)));—-找到id为textview的TextView，检查他的值与期盼的值作比较。

来看看怎么运行单元测试代码：
在相应的测试类上点击右键 —run-MainActivityInstrume…如下图所示：

来看看相应的单元测试结果：

好了这期就介绍到这里。