using-robolectric-correctly

What problem does it solve?

Robolectric unit tests often fail or behave inconsistently because of runner misconfiguration, missing Android resource setup, incorrect SDK/qualifier targeting, and forgetting to drain the paused main looper before assertions.

Core Features & Use Cases

• Runner choice & configuration discipline: Select AndroidJUnit4 versus RobolectricTestRunner based on whether the test uses Robolectric-specific APIs, and lock behavior with the correct @Config(minSdk / sdk / qualifiers / application).
• Android resources that actually load on the JVM: Ensure unit tests can access R.*, Resources, layouts, and themes by enabling includeAndroidResources.
• Looper draining to make callbacks deterministic: Properly advance/drain paused Handler/Looper work using ShadowLooper and shadowOf(Looper.getMainLooper()).idle() before asserting outcomes.
• Shadows that map to real Android behavior gaps: Use common shadows (ShadowApplication, ShadowLog, ShadowLooper, ShadowPackageManager, ShadowSystemClock) and shadowOf(...) to validate system interactions.
• Modern sharedTest migration for AGP 7.2+: Avoid broken legacy sharedTest srcDir sharing and instead use androidHostTest + androidDeviceTest (or a shared module/KMP setup) for running the same logical tests on both runtimes.

Quick Start

Ask an AI to configure Robolectric for a JVM unit test suite by using AndroidJUnit4 with the right @Config matrix, enabling includeAndroidResources, and adding looper draining via ShadowLooper before assertions.