A thin runtime-dispatched shim over test-runner primitives, so the same test file runs on Bun, Deno, and Node.js 24.2+. That is mostly possible already, thanks to those runtimes' support for the Node testing API, but afterEach/beforeEach specifically do not work across all 3 runtimes without some kind of shim.

As of 2026-04-19, these things are true:

• Node's node:test works on Node and Bun, but Deno's node:test compat shim does not implement afterEach/beforeEach. Calling them under Deno throws Not implemented: test.afterEach.

• Deno's @std/testing/bdd works on Deno, but it references the Deno global unconditionally at runtime, and therefore crashes on Node and Bun with ReferenceError: Deno is not defined.

Both modules can be imported cleanly under every environment; only specific calls fail on the wrong runtime. This package picks the right implementation at runtime and re-exports it, so tests import one stable surface.

This is obviously hacky; hopefully this is temporary — if either @std/bdd becomes cross-runtime, or Deno implements the remaining bits of Node's API, then this package can be retired.

# Deno
deno add jsr:@axhxrx/test

# Bun
bunx jsr add @axhxrx/test

# Node / pnpm / npm
npx jsr add @axhxrx/test

import { afterEach, beforeEach, describe, test } from '@axhxrx/test';
import { expect } from '@std/expect';

describe('widgets', () =>
{
  let widget: Widget;

  beforeEach(() => { widget = new Widget(); });
  afterEach(() => { widget.dispose(); });

  test('has a handle', () => { expect(widget.handle).toBeDefined(); });
});

Run the same file under any runtime:

bun test path/to/file.test.ts
node --test path/to/file.test.ts
deno test -A path/to/file.test.ts

expect is NOT re-exported — get it from @std/expect directly. It already works on every runtime without a shim.

If your tests produce high-volume stdout, or spawn subprocesses whose output flows back through the test process, Node's default per-file process isolation can hit an IPC framing bug that surfaces as:

Error: Unable to deserialize cloned data due to invalid or unsupported version.

Workaround: run Node tests with --test-isolation=none (everything runs in one process, no IPC). Bun and Deno are unaffected. This only hits when doing weird stuff like running tests that for whatever reason invoke processes that spew huge amounts of output that you then consume. Not super common, but definitely a lurking problem for those kinds of tests.

MIT

• 2026-04-19 🧃 0.1.1 — juice that JSR score... 90% more documented symbols!

• 2026-04-19 📦 0.1.0 — initial implementation of small hack for @std-only cross-runtime tests