Add concurrency testing patterns to write-unit-tests skill#13300
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Covers runTest + advanceUntilIdle + async/await pattern for testing coroutines with real I/O, mutex queuing assertions, and common mistakes. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Committed-By-Agent: claude
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| // Coroutine is now suspended on the network call. | ||
| // Assert mid-flight state here. | ||
| assertThat(systemUnderTest.isLoading.value).isTrue() |
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These should really use turbines, right?
| fun `mutex is locked during mutation`() = runTest { | ||
| val holdResponse = CountDownLatch(1) | ||
| networkRule.checkoutUpdate { response -> | ||
| holdResponse.await() |
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We should really have timeouts for all these, even if something unreasonable like 10 seconds.
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| | Do | Don't | | ||
| |----|-------| | ||
| | `async { }` + `await()` | `launch { }` + `join()` | |
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Why not launch/join?
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Ahh, I see -- it's explained below. Makes sense to me.
- Turbine .test { } for asserting StateFlow transitions (false -> true -> false)
- CountDownLatch for asserting request ordering (negative + positive)
- Remove .value recommendation; prefer Turbine for StateFlow assertions
- Add timeouts to latch awaits in mock handlers
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Committed-By-Agent: claude
jaynewstrom-stripe
approved these changes
Jun 26, 2026
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Summary
write-unit-testsskillrunTest+advanceUntilIdle()+async/await()pattern for testing coroutines that involve real network I/O (NetworkRule/OkHttp)Context
Learned from code review on #13296 where timing-dependent tests needed to be rewritten using deterministic coroutine test patterns.
Test plan
🤖 Generated with Claude Code