How Espresso Works
summary
Explains Espresso 3.0 internals: matchers use Hamcrest, onView builds a Dagger 2-backed ViewInteraction with a UIController and ViewFinder, and calling onView alone does nothing so always follow with check or perform. Espresso waits by looping the main thread and reflectively dispatching queued messages until idling resources (registered via IdlingRegistry) and async tasks are idle, avoiding sleeps; ActivityTestRule launches activities via Instrumentation with a background-thread timeout (~45s).
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chapters (7)
- 0:00Introduction to Espresso
- 1:37Breaking down Espresso assertions
- 6:33How onView creates ViewInteraction
- 10:54How check executes on UI thread
- 22:31Finding views in view hierarchy
- 26:00View assertions and matchers
- 30:38Launching activities in tests
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