以下为activity_mian代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.gxd.hellowordhw.MainActivity"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />

    <EditText

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/editText" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="SAY HELLO!"
        android:id="@+id/button"
        android:layout_gravity="center_horizontal" />

</LinearLayout>


以下为Mainactivity代码：

package com.example.gxd.hellowordhw;

import android.support.v7.app.AppCompatActivity;
        import android.os.Bundle;
        import android.view.View;
        import android.widget.EditText;
        import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

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

以下为MainactivityText代码：
public class MainActivityTest {
     private static final String STRING_TO_BE_TYPEDTO = "Peter";
    @Rule
    public ActivityTestRule<MainActivity> mActivityTestRule = new ActivityTestRule<>(MainActivity.class);

    @Test
    public void testSayHello() throws Exception {

        onView(withId(R.id.editText)).perform(TestRule(STRING_TO_BE_TYPEDTO),closeSoftKeyboard);
        onView(withId(R.id.button)).perform(click());
        String expectedText="Hello,"+ STRING_TO_BE_TYPEDTO +"!";
        onView(withId(R.id.textview)).check(matches(withText(expectedText)));


    }


}

以下为build.gradle代码：

apply plugin: ‘com.android.application‘

android {
    compileSdkVersion 23
    buildToolsVersion "24.0.2"

    defaultConfig {
        applicationId "com.example.gxd.hellowordhw"
        minSdkVersion 19
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
        //add for test
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile(‘proguard-android.txt‘), ‘proguard-rules.pro‘
        }
    }
}

dependencies {
    compile fileTree(dir: ‘libs‘, include: [‘*.jar‘])
    testCompile ‘junit:junit:4.12‘
    compile ‘com.android.support:appcompat-v7:23.4.0‘
    //add for test
    androidTestCompile ‘com.android.support.test.espresso:espresso-core:2.2.2‘, {
        exclude group: ‘com.android.support‘, module: ‘support-annotations‘
    }
}
布局：

Android Studio中进行单元测试