Using Robolectric Correctly — Android On The JVM, Without The Footguns

Robolectric simulates Android on the JVM by swapping in pure-Java reimplementations of system classes ("shadows"). It is fast (10-100x vs an emulator) but not an emulator: no real RenderThread, no real Binder, no real GPU. This skill locks down the runner choice, the @Config matrix, the looper draining ritual, and the AGP 7.2+ sharedTest gotcha. Compose-on-Robolectric specifics live in ../../../compose/synchronization/controlling-the-test-clock/SKILL.md.

When to use this skill