Entry Point

import { it, expect } from "@effect/vitest"

Feature Description

it.effect

Injects TestContext (includes TestClock )

it.live

Uses live Effect environment (real clock, logging)

it.scoped

Provides a Scope for resource management

it.scopedLive

Combines scoped

• live

it.flakyTest

Retries flaky tests until success or timeout

Basic Tests

import { it, expect } from "@effect/vitest" import { Effect } from "effect"

it.effect("test success", () => Effect.gen(function* () { const result = yield* Effect.succeed(42) expect(result).toBe(42) }) )

Testing Failures with Exit

import { it, expect } from "@effect/vitest" import { Effect, Exit } from "effect"

it.effect("test failure", () => Effect.gen(function* () { const result = yield* Effect.exit(Effect.fail("oops")) expect(result).toStrictEqual(Exit.fail("oops")) }) )

TestClock

it.effect provides TestClock starting at 0 . Use it.live for real time.

import { it } from "@effect/vitest" import { Clock, Effect, TestClock } from "effect"

it.effect("with simulated time", () => Effect.gen(function* () { yield* TestClock.adjust("1000 millis") const now = yield* Clock.currentTimeMillis // now === 1000 }) )

it.live("with real time", () => Effect.gen(function* () { const now = yield* Clock.currentTimeMillis // now === actual system time }) )

Scoped Tests

Use it.scoped when your test acquires resources.

import { it } from "@effect/vitest" import { Console, Effect } from "effect"

const resource = Effect.acquireRelease( Console.log("acquire"), () => Console.log("release") )

it.scoped("manages resources", () => Effect.gen(function* () { yield* resource // automatically released after test }) )

Flaky Tests

import { it } from "@effect/vitest" import { Effect, Random } from "effect"

const flaky = Effect.gen(function* () { if (yield* Random.nextBoolean) return yield* Effect.fail("random failure") })

it.effect("retry until success", () => it.flakyTest(flaky, "5 seconds") )

Test Modifiers

it.effect.skip("skipped test", () => Effect.void) it.effect.only("run only this", () => Effect.void) it.effect.fails("expected to fail", () => Effect.fail("expected"))

Logging

Logging is suppressed in it.effect . Enable with custom logger or it.live :

import { it } from "@effect/vitest" import { Effect, Logger } from "effect"

it.effect("with logging", () => Effect.log("visible").pipe(Effect.provide(Logger.pretty)) )

it.live("logging enabled by default", () => Effect.log("visible") )