Lifecycle hooks

The test runner supports the following lifecycle hooks. This is useful for loading test fixtures, mocking data, and configuring the test environment.

Perform per-test setup and teardown logic with beforeEach and afterEach.

import { beforeEach, afterEach } from "bun:test";

beforeEach(() => {
  console.log("running test.");
});

afterEach(() => {
  console.log("done with test.");
});

// tests...

Perform per-scope setup and teardown logic with beforeAll and afterAll. The scope is determined by where the hook is defined.

To scope the hooks to a particular describe block:

import { describe, beforeAll } from "bun:test";

describe("test group", () => {
  beforeAll(() => {
    // setup
  });

  // tests...
});

To scope the hooks to a test file:

import { describe, beforeAll } from "bun:test";

beforeAll(() => {
  // setup
});

describe("test group", () => {
  // tests...
});

To scope the hooks to an entire multi-file test run, define the hooks in a separate file.

import { beforeAll, afterAll } from "bun:test";

beforeAll(() => {
  // global setup
});

afterAll(() => {
  // global teardown
});

Then use --preload to run the setup script before any test files.

$ bun test --preload ./setup.ts

To avoid typing --preload every time you run tests, it can be added to your bunfig.toml:

[test]
preload = ["./setup.ts"]