kp-testing-coroutines

One-line summary

Use runTest { … } + a TestDispatcher for fast, deterministic tests of coroutine code — virtual time replaces real delay, and dispatcher injection makes your production code testable without runBlocking.

When to use this skill

• Writing unit tests for suspend fun or Flow.
• Testing time-dependent behavior (timeouts, delays, debounce, sample) without real waiting.
• Testing concurrent coroutines and their interactions.
• Replacing slow / flaky runBlocking test setups.

When NOT to use this skill

• The code isn't actually suspending and no coroutines are involved — use a regular test.
• Integration tests that genuinely need real time and threads — runBlocking may still be appropriate (rarely).

Core content

runTest { … } is the canonical entry point from kotlinx-coroutines-test. It runs your test body as a coroutine with a TestScope that has a TestDispatcher and a virtual clock.