effect-testing-mocking

Deterministic testing isolates services by injecting mock layers and controlling time with a TestClock. Use Layer.succeed to provide test implementations of dependencies, eliminating external calls and making tests fast and reproducible.

Mock layers provide explicit test implementations per test using the Layer pattern. Each test receives its own mock dependencies, preventing cross-test interference and aligning with real service architecture patterns like Layer.ts.

TestClock provides deterministic time control within test environments. Advance time programmatically to drive asynchronous behavior and verify outcomes without waiting for real delays, keeping tests focused and fast.

Yes. Smoke tests benefit from the same mock-layer and deterministic-clock patterns used in unit tests. This approach prevents IO leakage, maintains test speed, and verifies critical service paths without external dependencies.

You need testable services structured with layers, mock implementations ready for each dependency, and familiarity with Layer, TestClock, and TestContext patterns. These patterns align with real API conventions already in use.