There were added new classes to test Activities, such as ActivityScenarioRule and ActivityScenario And there is no documentation how to use them when you want put some extra data.
For now I've found two working ways, in short:
1) Use ActivityScenarioRule and put your extra in the method with @Before annotation using #onActivity. But, there would be unnecessary data for some test cases.
2) Second, use ActivityScenario with #launch(Class activityClass) when you dont need extra and #launch(Intent startActivityIntent) when you want put extra. But, this time I loose an ability to use #onActivity where can be placed common for all test cases
P.S. this is my first time of android testing :)