mirror of
https://github.com/oven-sh/bun
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1a23797e82
## Summary
Adds a new `test.serial()` API that forces tests to run serially even
when the `--concurrent` flag is passed. This is the opposite of
`test.concurrent()` which forces parallel execution.
## Motivation
Some tests genuinely need to run serially even in CI environments with
`--concurrent`:
- Database migration tests that must run in order
- Tests that modify shared global state
- Tests that use fixed ports or file system resources
- Tests that depend on timing or resource constraints
## Implementation
Changed `self_concurrent` from `bool` to `?bool`:
- `null` = default behavior (inherit from parent or use default)
- `true` = force concurrent execution
- `false` = force serial execution
## API Surface
```javascript
// Force serial execution
test.serial("database migration", async () => {
// This runs serially even with --concurrent flag
});
// All modifiers work
test.serial.skip("skip this serial test", () => {});
test.serial.todo("implement this serial test");
test.serial.only("only run this serial test", () => {});
test.serial.each([[1], [2]])("serial test %i", (n) => {});
test.serial.if(condition)("conditional serial", () => {});
// Works with describe too
describe.serial("serial test suite", () => {
test("test 1", () => {}); // runs serially
test("test 2", () => {}); // runs serially
});
// Explicit test-level settings override describe-level
describe.concurrent("concurrent suite", () => {
test.serial("this runs serially", () => {}); // serial wins
test("this runs concurrently", () => {});
});
```
## Test Coverage
Comprehensive tests added including:
- Basic `test.serial()` functionality
- All modifiers (skip, todo, only, each, if)
- `describe.serial()` blocks
- Mixing serial and concurrent tests in same describe block
- Nested describe blocks with conflicting settings
- Explicit overrides (test.serial in describe.concurrent and vice versa)
All 36 tests pass ✅
## Example
```javascript
// Without this PR - these tests might run in parallel with --concurrent
test("migrate database schema v1", async () => { await migrateV1(); });
test("migrate database schema v2", async () => { await migrateV2(); });
test("migrate database schema v3", async () => { await migrateV3(); });
// With this PR - guaranteed serial execution
test.serial("migrate database schema v1", async () => { await migrateV1(); });
test.serial("migrate database schema v2", async () => { await migrateV2(); });
test.serial("migrate database schema v3", async () => { await migrateV3(); });
```
🤖 Generated with [Claude Code](https://claude.ai/code)
---------
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Tests
Finding tests
Tests are located in the test/ directory and are organized using the following structure:
test/js/- tests for JavaScript APIs.cli/- tests for commands, configs, and stdout.bundler/- tests for the transpiler/bundler.regression/- tests that reproduce a specific issue.harness.ts- utility functions that can be imported from any test.
The tests in test/js/ directory are further categorized by the type of API.
test/js/bun/- tests forBun-specific APIs.node/- tests for Node.js APIs.web/- tests for Web APIs, likefetch().first_party/- tests for npm packages that are built-in, likeundici.third_party/- tests for npm packages that are not built-in, but are popular, likeesbuild.
Running tests
To run a test, use Bun's built-in test command: bun test.
bun test # Run all tests
bun test js/bun # Only run tests in a directory
bun test sqlite.test.ts # Only run a specific test
If you encounter lots of errors, try running bun install, then trying again.
Writing tests
Tests are written in TypeScript (preferred) or JavaScript using Jest's describe(), test(), and expect() APIs.
import { describe, test, expect } from "bun:test";
import { gcTick } from "harness";
describe("TextEncoder", () => {
test("can encode a string", async () => {
const encoder = new TextEncoder();
const actual = encoder.encode("bun");
await gcTick();
expect(actual).toBe(new Uint8Array([0x62, 0x75, 0x6E]));
});
});
If you are fixing a bug that was reported from a GitHub issue, remember to add a test in the test/regression/ directory.
// test/regression/issue/02005.test.ts
import { it, expect } from "bun:test";
it("regex literal should work with non-latin1", () => {
const text = "这是一段要替换的文字";
expect(text.replace(new RegExp("要替换"), "")).toBe("这是一段的文字");
expect(text.replace(/要替换/, "")).toBe("这是一段的文字");
});
In the future, a bot will automatically close or re-open issues when a regression is detected or resolved.
Zig tests
These tests live in various .zig files throughout Bun's codebase, leveraging Zig's builtin test keyword.
Currently, they're not run automatically nor is there a simple way to run all of them. We will make this better soon.
TypeScript
Test files should be written in TypeScript. The types in packages/bun-types should be updated to support all new APIs. Changes to the .d.ts files in packages/bun-types will be immediately reflected in test files; no build step is necessary.
Writing a test will often require using invalid syntax, e.g. when checking for errors when an invalid input is passed to a function. TypeScript provides a number of escape hatches here.
// @ts-expect-error- This should be your first choice. It tells TypeScript that the next line should fail typechecking.// @ts-ignore- Ignore the next line entirely.// @ts-nocheck- Put this at the top of the file to disable typechecking on the entire file. Useful for autogenerated test files, or when ignoring/disabling type checks an a per-line basis is too onerous.