effect-bun-test

Effect testing utilities for Bun.

Install

bun add -d effect-bun-test

Usage

import { Effect, TestClock } from "effect";
import { describe, it, expect, yieldFibers } from "effect-bun-test";

describe("my feature", () => {
  // Run with TestContext (includes TestClock)
  it.effect("handles time-based logic", () =>
    Effect.gen(function* () {
      yield* TestClock.adjust("1 second");
      expect(true).toBe(true);
    }),
  );

  // Run scoped effect with TestContext
  it.scoped("cleans up resources", () =>
    Effect.gen(function* () {
      const resource = yield* Effect.acquireRelease(Effect.succeed("handle"), () =>
        Effect.log("released"),
      );
      // resource auto-released after test
    }),
  );

  // Run with real clock (no TestContext)
  it.live("uses actual delays", () =>
    Effect.gen(function* () {
      yield* Effect.sleep("10 millis");
    }),
  );

  // Yield to forked fibers
  it.effect("waits for async work", () =>
    Effect.gen(function* () {
      let done = false;
      yield* Effect.fork(
        Effect.sync(() => {
          done = true;
        }),
      );
      yield* yieldFibers;
      expect(done).toBe(true);
    }),
  );
});

API

Test Runners

Method	TestContext	Scope	Use Case
it.effect	✓		Time-controlled tests
it.scoped	✓	✓	Tests with resource cleanup
it.live			Real clock tests
it.scopedLive		✓	Real clock + resource cleanup

Utilities

• yieldFibers - Yield to allow forked fibers to process (use after fork or send)
• describe, test, expect - Re-exported from bun:test

License

MIT