title: I did not add @RunWith(AndroidJUnit4.class) in my instrumentation tests
body: <p>The android's testing documentation and a lot of other tutorials keep saying that I should include this line <code>@RunWith(AndroidJUnit4.class)</code> in all of my instrumentation tests. But, I did not add this annotation in any of my instr. tests and still all of them are running fine. So,</p>
  
  <p>What is happening and Why to add  <code>@RunWith(AndroidJUnit4.class)</code> above instr. test classes?</p>