Unit, integration, UI tests are part of the famous test pyramid, different tools were used in order to full fill it, but still today there are lot of issues about how to execute it in a proper manner and how to sync all environments (local, ci, etc) in order to satisfy all the testing criteria, and having a good reports.

From IO 2018 with the announcement of project Nitrogen, Google'd like to "nitrogenize" our tests creating a single entry point and solve all issues
we had in the past. With October release of Robolectric 4.0 and androidx.test 1.0.0, both testing environments are converging on a set of common test APIs. Robolectric now supports the AndroidJUnit4 test runner, ActivityTestRule, and Espresso for interacting with UI components.

Let's see togheter how to organise different levels of our 'test pyramid', with a focus to the last news/releases in order ot be ready for the Nitrogen release.