title: Cannot resolve symbol InstantTaskExecutorRule
body: <p>I open example code BasicRxJavaSample (from this article <a href="https://medium.com/google-developers/room-rxjava-acb0cd4f3757" rel="noreferrer">Room+RxJava</a>) 
  The main thing is there:</p>
  
  <pre><code>@Rule
  public InstantTaskExecutorRule instantTaskExecutorRule = 
      new InstantTaskExecutorRule();
  </code></pre>
  
  <p>And BasicRxJavaSample is all ok.
  But I can not apply this in my test.
  That's what's going on:</p>
  
  <p><strong><em>Cannot resolve symbol InstantTaskExecutorRule</em></strong></p>
  
  <p><a href="https://i.stack.imgur.com/EO3gz.png" rel="noreferrer"><img src="https://i.stack.imgur.com/EO3gz.png" alt="enter image description here"></a></p>
  
  <p>And manual import does not work:</p>
  
  <p><a href="https://i.stack.imgur.com/L61WN.png" rel="noreferrer"><img src="https://i.stack.imgur.com/L61WN.png" alt="enter image description here"></a></p>
  
  <p>My autocompletion works like this
  <a href="https://i.stack.imgur.com/1Qgzy.png" rel="noreferrer"><img src="https://i.stack.imgur.com/1Qgzy.png" alt="enter image description here"></a></p>
  
  <p>But should be so</p>
  
  <p><a href="https://i.stack.imgur.com/JzFev.png" rel="noreferrer"><img src="https://i.stack.imgur.com/JzFev.png" alt="enter image description here"></a></p>
  
  <p>My app build.gradle (<a href="https://gist.github.com/tim4dev/b95f36ccd2f32d0603457a281ef6bf58" rel="noreferrer">full gradle here</a>):</p>
  
  <pre><code>// tests
  testImplementation 'junit:junit:4.12'
  androidTestCompile "com.android.support:support-annotations:$supportVersion"
  testImplementation "android.arch.core:core-testing:$archVersion"
  // Test helpers for Room
  testImplementation "android.arch.persistence.room:testing:1.0.0"
  // https://github.com/mockito/mockito
  testImplementation 'org.mockito:mockito-core:2.13.0'
  androidTestImplementation 'org.mockito:mockito-android:2.13.0'
  // AndroidJUnitRunner and JUnit Rules
  androidTestImplementation 'com.android.support.test:rules:1.0.1'
  androidTestImplementation 'com.android.support.test:runner:1.0.1'
  // https://developer.android.com/topic/libraries/testing-support-library/packages.html
  androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
  androidTestCompile 'com.android.support.test.espresso:espresso-idling-resource:3.0.1'
  </code></pre>