1.首先，在后缀为AndroidTest的文件夹内建立一个MainActivityInstrumentedTest的Java文件,

package com.example.pj.git;

import android.support.test.filters.LargeTest;
import android.support.test.rule.ActivityTestRule;
import android.support.test.runner.AndroidJUnit4;
import android.view.View;

import org.hamcrest.Matcher;
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;

/**
 * Created by pj on 2017/3/15.
 */
@RunWith(AndroidJUnit4.class)
@LargeTest
public class MainActivityInstrumentationTest {
    private static final String STRING_TO_BE_TYPED = "Peter";

    @Rule
    public ActivityTestRule<MainActivity> mActivityRule = new ActivityTestRule<MainActivity>(MainActivity.class);

    @Test
    public void sayHello() {
        onView(withId(R.id.et)).perform(typeText(STRING_TO_BE_TYPED), closeSoftKeyboard());
        onView(withText("Say hello!")).perform(click());
        String expectedText = "Hello," + STRING_TO_BE_TYPED + "!";
        onView(withId(R.id.tv)).check(matches(withText(expectedText)));
    }
}

2.然后在模拟器上运行MainActivityInstrumentedTest,如果运行成功会提示

如果运行失败会提示

在Android Studio环境下使用ESPRESSO 测试框架进行UI测试