title: 'android.support.test.espresso does not exist' when I want to use it to individual apk test
body: <p>I need to do some auto testing jobs to an Android application without its source code. I found both robotium and espresso can do this job, I decided to use espresso because its Google support.</p>
  
  <p>I would like to sign both the target apk and espresso test apk with the same signature, the target apk is the same as <a href="http://developer.android.com/training/basics/firstapp/starting-activity.html" rel="noreferrer">this sample</a>. </p>
  
  <p><img src="https://i.stack.imgur.com/TZQSO.png" alt="enter image description here"></p>
  
  <p>When I start to coding the espresso test apk, I did the following jobs.</p>
  
  <p>The build.gradle in Module:app:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 21
      buildToolsVersion "21.1.2"
  
      defaultConfig {
          applicationId "tk.deedog.i01test"
          minSdkVersion 15
          targetSdkVersion 21
          versionCode 1
          versionName "1.0"
  
          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'])
      compile 'com.android.support:appcompat-v7:21.0.3'
  
      androidTestCompile 'com.android.support.test.espresso:espresso-core:2.0'
      androidTestCompile 'com.android.support.test:testing-support-lib:0.1'
  }
  </code></pre>
  
  <p>The source code of my I01Test.java:</p>
  
  <pre><code>package tk.deedog.i01test;
  
  import android.app.Activity;
  import android.test.ActivityInstrumentationTestCase2;
  
  import static android.support.test.espresso.Espresso.onView;
  import static android.support.test.espresso.action.ViewActions.click;
  import static android.support.test.espresso.matcher.ViewMatchers.withText;
  
  
  public class I01Test extends ActivityInstrumentationTestCase2 {
      private static final String LAUNCHER_ACTIVITY_FULL_CLASSNAME = "tk.tubabe.instrustmen101.Instruments101";
      private static Class&lt;?&gt; launcherActivityClass;
      Activity i101Acitvity;
  
      static {
          try {
              launcherActivityClass = Class.forName(LAUNCHER_ACTIVITY_FULL_CLASSNAME);
          } catch (ClassNotFoundException e) {
              throw new RuntimeException(e);
          }
      }
  
      public I01Test() {
          super(launcherActivityClass);
      }
  
      @Override
      protected void setUp() throws Exception {
          super.setUp();
          i101Acitvity = getActivity();
      }
  
      @Override
      protected void tearDown() throws Exception {
          super.tearDown();
      }
  
      public void testButtonClick() {
          onView(withText("Send")).perform(click());
      }
  }
  </code></pre>
  
  <p>When I tried to run this program, Android studio told me that <code>Error:(6, 44) error: package android.support.test.espresso does not exist</code>.</p>