Run your tests with the Bun test runner

Bun has a built-in test runner with a Jest-like expect API.

To use it, run bun test from your project directory. The test runner recursively searches for files matching the following patterns and runs the tests they contain.

File Tree

*.test.{js|jsx|ts|tsx}
*_test.{js|jsx|ts|tsx}
*.spec.{js|jsx|ts|tsx}
*_spec.{js|jsx|ts|tsx}

Here’s the output of a typical run: three test files (test.test.js, test2.test.js, and test3.test.js), each containing two tests (add and multiply).

terminal

bun test

test.test.js:
✓ add [0.87ms]
✓ multiply [0.02ms]

test2.test.js:
✓ add [0.72ms]
✓ multiply [0.01ms]

test3.test.js:
✓ add [0.54ms]
✓ multiply [0.01ms]

 6 pass
 0 fail
 6 expect() calls
Ran 6 tests across 3 files. [9.00ms]

To only run certain test files, pass a positional argument to bun test. The runner only executes files with that argument in their path.

terminal

bun test test3

test3.test.js:
✓ add [1.40ms]
✓ multiply [0.03ms]

 2 pass
 0 fail
 2 expect() calls
Ran 2 tests across 1 files. [15.00ms]

Every test has a name: the first argument to the test function. Tests can also be grouped into suites with describe.

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

describe("math", () => {
  test("add", () => {
    expect(2 + 2).toEqual(4);
  });

  test("multiply", () => {
    expect(2 * 2).toEqual(4);
  });
});

To filter tests by name, use the -t/--test-name-pattern flag. -t add only runs tests with “add” in the name. The pattern matches test names defined with test and suite names defined with describe.

terminal

bun test -t add

test.test.js:
✓ add [1.79ms]

test2.test.js:
✓ add [2.30ms]

test3.test.js:
✓ add [0.32ms]

 3 pass
 3 filtered out
 0 fail
 3 expect() calls
Ran 3 tests across 3 files. [59.00ms]

See bun test.