effect-v4-testing

Use when writing, reviewing, or fixing tests for Effect v4 code with @effect/vitest — it.effect + Effect.gen as the default runner, asserting typed errors via Effect.flip or Effect.result (Exit + Cause for defects), providing test/mock layers with layer(...) for any service in R (owned or consumed), fault-injecting one method of a real layer, property tests with it.effect.prop over a Schema, TestClock for time-dependent logic, converting a plain-Vitest repo, and the mutate-the-edges discipline for proving a suite can actually fail — the discriminating input wrong in exactly one way, per-clause and per-path mutation, and the positive control a "nothing found" result needs before it's believed. Also triggers on: Tests: 0/0 passed lying while the exit code is honest, TestClock at the epoch (1970), layer() memoizing while Effect.provide does not, TestConsole swallowing Effect.log* through ConsoleRef, vi.mock must import vi from vitest, structural checks over source text.