You can organize the execution of your instrumented unit tests defining a Suite.

/**
 * Runs all unit tests.
 */
@RunWith(Suite.class)
@Suite.SuiteClasses({MyTest1.class , 
         MyTest2.class, 
         MyTest3.class})
public class AndroidTestSuite {}

Then in AndroidStudio you can run with gradle or setting a new configuration like:

http://i.stack.imgur.com/2skwt.png

Test suites can be nested.