effect-patterns-testing

Testing asynchronous Effect-TS code deterministically involves running effects with `Effect.runPromise` and asserting results directly. You control time-dependent logic using `TestClock` to ensure consistent outcomes without real delays.

Mocking service dependencies in Effect-TS tests uses `Effect.provideService` to inject test implementations. This isolates units by replacing real service dependencies with controlled test versions during execution.

Yes, you can use vitest with Effect-TS for testing streams by utilizing `Stream.runCollect`. This pattern allows you to collect stream emissions into an array, enabling standard assertions on the asynchronous stream output.

The best way to test time-dependent logic in Effect-TS is using the `TestClock`. It allows you to manually adjust the `Clock` service, making time-based asynchronous operations deterministic and eliminating real-time waiting during tests.

While vitest is a primary keyword, the core patterns focus on Effect-TS execution and mocking. You run effects using `Effect.runPromise`, which works within vitest or similar test runners supporting promise assertions.