本Sample演示了键盘输入，然后点击按钮显示在同一个Activity中的TextView以及不同Activity的TextView的UI自动化测试。
界面图
被测试的工程项目
被测试的Sample工程很简单，一个EditView一个TextView，两个Button，键盘输入内容后，点击“CHANGE TEXT”按钮后TextView将 显示输入内容，点击“OPEN ACTIVITY AND CHANGE TEXT”按钮后将打开新的Activity并显示输入内容。
Espresso的工程项目
模拟键盘输入“Espresso”，然后对比输入字符与预期字符是否一致。一致则测试通过，不一致而显示期望值(Expect)和实际值(Got)。
完整的Sample代码
整个测试工程的代码不足100行(包括注释)，所以直接贴出代码进行分析
package com.example.android.testing.espresso.BasicSample;import android.app.Activity;
import android.support.test.espresso.action.ViewActions;
import android.support.test.espresso.matcher.ViewMatchers;
import android.support.test.filters.LargeTest;
import android.support.test.rule.ActivityTestRule;
import android.support.test.runner.AndroidJUnit4;
import android.test.ActivityInstrumentationTestCase2;import org.junit.Before;
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;/*** Basic tests showcasing simple view matchers and actions like {@link ViewMatchers#withId},* {@link ViewActions#click} and {@link ViewActions#typeText}.* <p>* Note that there is no need to tell Espresso that a view is in a different {@link Activity}.*/
@RunWith(AndroidJUnit4.class)
@LargeTest
public class ChangeTextBehaviorTest {
public static final String STRING_TO_BE_TYPED = "Espresso";/*** A JUnit {@link Rule @Rule} to launch your activity under test. This is a replacement* for {@link ActivityInstrumentationTestCase2}.* <p>* Rules are interceptors which are executed for each test method and will run before* any of your setup code in the {@link Before @Before} method.* <p>* {@link ActivityTestRule} will create and launch of the activity for you and also expose* the activity under test. To get a reference to the activity you can use* the {@link ActivityTestRule#getActivity()} method.*/@Rulepublic ActivityTestRule<MainActivity> mActivityRule = new ActivityTestRule<>(MainActivity.class);@Testpublic void changeText_sameActivity() {// Type text and then press the button.onView(withId(R.id.editTextUserInput)).perform(typeText(STRING_TO_BE_TYPED + "\n"), closeSoftKeyboard());onView(withId(R.id.changeTextBt)).perform(click());// Check that the text was changed.onView(withId(R.id.textToBeChanged)).check(matches(withText(STRING_TO_BE_TYPED)));}@Testpublic void changeText_newActivity() {// Type text and then press the button.onView(withId(R.id.editTextUserInput)).perform(typeText(STRING_TO_BE_TYPED + "\n"),closeSoftKeyboard());onView(withId(R.id.activityChangeTextBtn)).perform(click());// This view is in a different Activity, no need to tell Espresso.onView(withId(R.id.show_text_view)).check(matches(withText(STRING_TO_BE_TYPED)));}
}代码分析
1.类注释中说明，没有必要告诉Espresso被测的view是在不同的Activity中,也就是直接使用 onView()即可获取相应的view
2.@Rule 注解是取代了ActivityInstrumentationTestCase2，是一个拦截器(interceptor),会在@Before的代码运行之前运行。
3. onView()可以根据view的id，hint，text等获取相应的view； perform()属于ViewAction，常见的click，doubleClick等； check()属于ViewInteraction，校验交互后的结果。
4.在changeText_newActivity()方法中，即使跳转了Activity，也直接使用 onView()即可获取相应的view。
运行效果
注意事项
将输入法换成Android自带键盘，如果使用搜狗、百度等其他中文输入法，则需要将输入的字符串加多一个 \n，不然就会测试失败(仅获取了一个大写字母)