Effect test helpers for Rstest. This package re-exports @rstest/core and adds Effect-aware tests, shared layers, test services, and property testing.
pnpm add -D effect-rstest @rstest/coreThe initial release targets Effect 4 RC and Rstest 0.11.
Use it.effect for tests with TestClock and TestConsole, or it.live for the live Effect environment. Both variants create and close a fresh Scope for each test.
import { Effect, Fiber } from "effect"
import { assert, it } from "effect-rstest"
import { TestClock } from "effect/testing"
it.effect("advances virtual time", () =>
Effect.gen(function*() {
const fiber = yield* Effect.forkChild(Effect.sleep(60_000))
yield* TestClock.adjust(60_000)
yield* Fiber.join(fiber)
assert.isTrue(true)
}))The test fiber receives Rstest's abort signal. If a test times out, the runner still reports the timeout, but an onTestFinished barrier waits for fiber settlement and scoped finalizers before later sequential tests and suite-layer release. The barrier does not impose a second cleanup timeout: a finalizer that never completes can prevent the suite from progressing. Successful non-void Effect values are discarded; ordinary failures and .fails outcomes retain their runner semantics.
Native hook boundary: Rstest runs native afterEach hooks before onTestFinished. On timeout, those hooks can run before Effect cleanup finishes; the settlement guarantee does not cover them. It also does not serialize tests explicitly scheduled concurrently.
Use layer or it.layer to share a layer across a group of tests. Named layers accept concurrent to override the enclosing suite.
Rstest's suite hook context has no abort signal. When setup exceeds an explicit layer timeout, or the inherited hookTimeout when omitted, suite teardown interrupts and awaits the setup fiber before closing its scope. This also releases resources acquired before an early setup failure. The teardown hook retains the same timeout: cleanup that exceeds it can outlive the hook and is not a bounded-cleanup guarantee. Hook failures remain runner failures. Named and unnamed layer blocks use the same lifecycle boundary.
import { Context, Effect, Layer } from "effect"
import { assert, it } from "effect-rstest"
class Api extends Context.Service<Api, { readonly status: Effect.Effect<number> }>()("Api") {}
const ApiLive = Layer.succeed(Api, { status: Effect.succeed(200) })
it.layer(ApiLive)("api", (it) => {
it.effect("returns a status", () =>
Effect.gen(function*() {
const api = yield* Api
assert.strictEqual(yield* api.status, 200)
}))
})Property tests accept Effect Schema and FastCheck Arbitrary values. They shrink callbacks that return false, throw, or fail with a non-interruption cause.
import { Effect, Schema } from "effect"
import { assert, it } from "effect-rstest"
it.effect.prop(
"addition is commutative",
[Schema.Int, Schema.Int],
([a, b]) => Effect.sync(() => assert.strictEqual(a + b, b + a))
)All three helpers accept both tuple and record inputs, mixing schemas and FastCheck arbitraries. Schemas are converted with Schema.toArbitrary(schema)(FastCheck); FastCheck arbitraries are used directly. For example, a synchronous property can use [Schema.Literal("schema"), FastCheck.integer()] or { label: Schema.Literal("schema"), count: FastCheck.integer() }. A schema must support arbitrary generation; this does not make every possible schema generatable.
Rstest modifiers remain available. Use it.effect.concurrent, it.effect.sequential, it.effect.skip, it.effect.only, it.effect.fails, it.effect.skipIf, and it.effect.runIf with Effect tests.
Call addEqualityTesters() from an Rstest setup file to opt in. When both compared values implement Effect's Equal protocol, the tester delegates to Equal.equals, including semantic inequality and nested comparisons. For other values it returns undefined, leaving plain-object equality and asymmetric matchers to Rstest. It does not replace Rstest's equality behavior globally.
MIT