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# bun test Fixes #8768, Fixes #14624, Fixes #20100, Fixes #19875, Fixes #14135, Fixes #20980, Fixes #21830, Fixes #5738, Fixes #19758, Fixes #12782, Fixes #5585, Fixes #9548, Might fix 5996 # New features: ## Concurrent tests Concurrent tests allow running multiple async tests at the same time. ```ts // concurrent.test.ts test.concurrent("this takes a while 1", async () => { await Bun.sleep(1000); }); test.concurrent("this takes a while 2", async () => { await Bun.sleep(1000); }); test.concurrent("this takes a while 3", async () => { await Bun.sleep(1000); }); ``` Without `.concurrent`, this test file takes 3 seconds to run because each one has to wait for the one before it to finish before it can start. With `.concurrent`, this file takes 1 second because all three sleeps can run at once. ``` $> bun-after test concurrent concurrent.test.js: ✓ this takes a while 1 [1005.36ms] ✓ this takes a while 2 [1012.51ms] ✓ this takes a while 3 [1013.15ms] 3 pass 0 fail Ran 3 tests across 1 file. [1081.00ms] ``` To run all tests as concurrent, pass the `--concurrent` flag when running tests. Limitations: - concurrent tests cannot attribute `expect()` call counts to the test, meaning `expect.assertions()` does not function - concurrent tests cannot use `toMatchSnapshot`. `toMatchInlineSnapshot` is still supported. - `beforeAll`/`afterAll` will never be executed concurrently. `beforeEach`/`afterEach` will. ## Chaining Chaining multiple describe/test qualifiers is now allowed. Previously, it would fail. ```ts // chaining-test-qualifiers.test.ts test.failing.each([1, 2, 3])("each %i", async i => { throw new Error(i); }); ``` ``` $> bun-after test chaining-test-qualifiers a.test.js: ✓ each 1 ✓ each 2 ✓ each 3 ``` # Breaking changes: ## Describe ordering Previously, describe callbacks were called immediately. Now, they are deferred until the outer callback has finished running. The previous order matched Jest. The new order is similar to Vitest, but does not match exactly. ```ts // describe-ordering.test.ts describe("outer", () => { console.log("outer before"); describe("inner", () => { console.log("inner"); }); console.log("outer after"); }); ``` Before, this would print ``` $> bun-before test describe-ordering outer before inner outer after ``` Now, this will print ``` $> bun-after test describe-ordering outer before outer after inner ``` ## Test ordering Describes are no longer always called before tests. They are now in order. ```ts // test-ordering.test.ts test("one", () => {}); describe("scope", () => { test("two", () => {}); }); test("three", () => {}); ``` Before, this would print ``` $> bun-before test test-ordering ✓ scope > two ✓ one ✓ three ``` Now, this will print ``` $> bun-after test test-ordering ✓ one ✓ scope > two ✓ three ``` ## Preload hooks Previously, beforeAll in a preload ran before the first file and afterAll ran after the last file. Now, beforeAll will run at the start of each file and afterAll will run at the end of each file. This behaviour matches Jest and Vitest. ```ts // preload.ts beforeAll(() => console.log("preload: beforeAll")); afterAll(() => console.log("preload: afterAll")); ``` ```ts // preload-ordering-1.test.ts test("demonstration file 1", () => {}); ``` ```ts // preload-ordering-2.test.ts test("demonstration file 2", () => {}); ``` ``` $> bun-before test --preload=./preload preload-ordering preload-ordering-1.test.ts: preload: beforeAll ✓ demonstration file 1 preload-ordering-2.test.ts: ✓ demonstration file 2 preload: afterAll ``` ``` $> bun-after test --preload=./preload preload-ordering preload-ordering-1.test.ts: preload: beforeAll ✓ demonstration file 1 preload: afterAll preload-ordering-2.test.ts: preload: beforeAll ✓ demonstration file 2 preload: afterAll ``` ## Describe failures Current behaviour is that when an error is thrown inside a describe callback, none of the tests declared there will run. Now, describes declared inside will also not run. The new behaviour matches the behaviour of Jest and Vitest. ```ts // describe-failures.test.ts describe("erroring describe", () => { test("this test does not run because its describe failed", () => { expect(true).toBe(true); }); describe("inner describe", () => { console.log("does the inner describe callback get called?"); test("does the inner test run?", () => { expect(true).toBe(true); }); }); throw new Error("uh oh!"); }); ``` Before, the inner describe callback would be called and the inner test would run, although the outer test would not: ``` $> bun-before test describe-failures describe-failures.test.ts: does the inner describe callback get called? # Unhandled error between tests ------------------------------- 11 | throw new Error("uh oh!"); ^ error: uh oh! ------------------------------- ✓ erroring describe > inner describe > does the inner test run? 1 pass 0 fail 1 error 1 expect() calls Ran 1 test across 1 file. Exited with code [1] ``` Now, the inner describe callback is not called at all. ``` $> bun-after test describe-failures describe-failures.test.ts: # Unhandled error between tests ------------------------------- 11 | throw new Error("uh oh!"); ^ error: uh oh! ------------------------------- 0 pass 0 fail 1 error Ran 0 tests across 1 file. Exited with code [1] ``` ## Hook failures Previously, a beforeAll failure would skip subsequent beforeAll()s, the test, and the afterAll. Now, a beforeAll failure skips any subsequent beforeAll()s and the test, but not the afterAll. ```js beforeAll(() => { throw new Error("before all: uh oh!"); }); test("my test", () => { console.log("my test"); }); afterAll(() => console.log("after all")); ``` ``` $> bun-before test hook-failures Error: before all: uh oh! $> bun-after test hook-failures Error: before all: uh oh! after all ``` Previously, an async beforeEach failure would still allow the test to run. Now, an async beforeEach failure will prevent the test from running ```js beforeEach(() => { await 0; throw "uh oh!"; }); it("the test", async () => { console.log("does the test run?"); }); ``` ``` $> bun-before test async-beforeeach-failure does the test run? error: uh oh! uh oh! ✗ the test $> bun-after test async-beforeeach-failure error: uh oh! uh oh! ✗ the test ``` ## Hook timeouts Hooks will now time out, and can have their timeout configured in an options parameter ```js beforeAll(async () => { await Bun.sleep(1000); }, 500); test("my test", () => { console.log("ran my test"); }); ``` ``` $> bun-before test hook-timeouts ran my test Ran 1 test across 1 file. [1011.00ms] $> bun-after test hook-timeouts ✗ my test [501.15ms] ^ a beforeEach/afterEach hook timed out for this test. ``` ## Hook execution order beforeAll will now execute before the tests in the scope, rather than immediately when it is called. ```ts describe("d1", () => { beforeAll(() => { console.log("<d1>"); }); test("test", () => { console.log(" test"); }); afterAll(() => { console.log("</d1>"); }); }); describe("d2", () => { beforeAll(() => { console.log("<d2>"); }); test("test", () => { console.log(" test"); }); afterAll(() => { console.log("</d2>"); }); }); ``` ``` $> bun-before test ./beforeall-ordering.test.ts <d1> <d2> test </d1> test </d2> $> bun-after test ./beforeall-ordering.test.ts <d1> test </d1> <d2> test </d2> ``` ## test inside test test() inside test() now errors rather than silently failing. Support for this may be added in the future. ```ts test("outer", () => { console.log("outer"); test("inner", () => { console.log("inner"); }); }); ``` ``` $> bun-before test outer ✓ outer [0.06ms] 1 pass 0 fail Ran 1 test across 1 file. [8.00ms] $> bun-after test outer 1 | test("outer", () => { 2 | console.log("outer"); 3 | test("inner", () => { ^ error: Cannot call test() inside a test. Call it inside describe() instead. ✗ outer [0.71ms] 0 pass 1 fail ``` ## afterAll inside test afterAll inside a test is no longer allowed ```ts test("test 1", () => { afterAll(() => console.log("afterAll")); console.log("test 1"); }); test("test 2", () => { console.log("test 2"); }); ``` ``` $> bun-before test 1 ✓ test 1 [0.05ms] test 2 ✓ test 2 afterAll $> bun-after error: Cannot call afterAll() inside a test. Call it inside describe() instead. ✗ test 1 [1.00ms] test 2 ✓ test 2 [0.20ms] ``` # Only inside only Previously, an outer 'describe.only' would run all tests inside it even if there was an inner 'test.only'. Now, only the innermost only tests are executed. ```ts describe.only("outer", () => { test("one", () => console.log("should not run")); test.only("two", () => console.log("should run")); }); ``` ``` $> bun-before test should not run should run $> bun-after test should run ``` With no inner only, the outer only will still run all tests: ```ts describe.only("outer", () => { test("test 1", () => console.log("test 1 runs")); test("test 2", () => console.log("test 2 runs")); }); ``` # Potential follow-up work - [ ] for concurrent tests, display headers before console.log messages saying which test it is for - this will need async context or similar - refActiveExecutionEntry should also be able to know the current test even in test.concurrent - [ ] `test("rerun me", () => { console.log("run one time!"); });` `--rerun-each=3` <- this runs the first and third time but not the second time. fix. - [ ] should to cache the JSValue created from DoneCallback.callAsFunction - [ ] implement retry and rerun params for tests. - [ ] Remove finalizer on ScopeFunctions.zig by storing the data in 3 jsvalues passed in bind rather than using a custom class. We should also migrate off of the ClassGenerator for ScopeFunctions - [ ] support concurrent limit, how many concurrent tests are allowed to run at a time. ie `--concurrent-limit=25` - [ ] flag to run tests in random order - [ ] `test.failing` should have its own style in the same way `test.todo` passing marks as 'todo' insetead of 'passing'. right now it's `✓` which is confusing. - [ ] remove all instances of bun.jsc.Jest.Jest.current - [ ] test options should be in BunTestRoot - [ ] we will need one global still, stored in the globalobject/vm/?. but it should not be a Jest instance. - [ ] consider allowing test() inside test(), as well as afterEach and afterAll. could even allow describe() too. to do this we would switch from indices to pointers and they would be in a linked list. they would be allocated in memorypools for perf/locality. some special consideration is needed for making sure repeated tests lose their temporary items. this could also improve memory usage soomewhat. - [ ] consider using a jsc Bound Function rather than CallbackWithArgs. bound functions allow adding arguments and they are only one value for GC instead of many. and this removes our unnecessary three copies. - [ ] eliminate Strong.Safe. we should be using a C++ class instead. - [ ] consider modifying the junit reporter to print the whole describe tree at the end instead of trying to output as test results come in. and move it into its own file. - [ ] expect_call_count/expect_assertions is confusing. rename to `expect_calls`, `assert_expect_calls`. or something. - [ ] Should make line_no be an enum with a none option and a function to get if line nombers are enabled - [ ] looks like we don't need to use file_id anymore (remove `bun.jsc.Jest.Jest.runner.?.getOrPutFile(file_path).file_id;`, store the file path directly) - [ ] 'dot' test reporter like vitest? - [ ] `test.failing.if(false)` errors because it can't replace mode 'failing' with mode 'skip'. this should probably be allowed instead. - [ ] trigger timeout termination exception for `while(true) {}` - [ ] clean up unused callbacks. as soon as we advance to the next execution group, we can fully clean out the previous one. sometimes within an execution sequence we can do the same. - clean by swapping held values with undefined - [ ] structure cache for performance for donecallback/scopefunctions - [ ] consider migrating CallbackWithArgs to be a bound function. the length of the bound function can exclude the specified args. - [ ] setting both result and maybe_skip is not ideal, maybe there should be a function to do both at once? - [ ] try using a linked list rather than arraylist for describe/test children, see how it affects performance - [ ] consider a memory pool for describescope/executionentry. test if it improves performance. - [ ] consider making RefDataValue methods return the reason for failure rather than ?value. that way we can improve error messages. the reason could be a string or it could be a defined error set - [ ] instead of 'description orelse (unnamed)', let's have description default to 'unnamed' and not free it if it === the global that defines that - [ ] Add a phase before ordering results that inherits properties to the parents. (eg inherit only from the child and inherit has_callback from the child. and has_callback can be on describe/test individually rather than on base). then we won't have that happening in an init() function (terrible!) - [ ] this test was incidentally passing because resolves.pass() wasn't waiting for promise ``` test("fetching with Request object - issue #1527", async () => { const server = createServer((req, res) => { res.end(); }).listen(0); try { await once(server, "listening"); const body = JSON.stringify({ foo: "bar" }); const request = new Request(`http://localhost:${server.address().port}`, { method: "POST", body, }); expect(fetch(request)).resolves.pass(); } finally { server.closeAllConnections(); } }); ``` - [ ] the error "expect.assertions() is not supported in the describe phase, in concurrent tests, between tests, or after test execution has completed" is not very good. we should be able to identify which of those it is and print the right error for the context - [ ] consider: instead of storing weak pointers to BunTest, we can instead give the instance an id and check that it is correct when getting the current bun test instance from the ref - [ ] auto_killer: add three layers of auto_killer: - preload (includes file & test) - file (includes test) - test - that way at the end of the test, we kill the test processes. at the end of the file, we kill the file processes. at the end of all, we kill anything remaining. AsyncLocalStorage - store active_id & refdatavalue. active_id is a replacement for the above weak pointers thing. refdatavalue is for determining which test it is. this probably fits in 2×u64 - use for auto_killer so timeouts can kill even in concurrent tests --------- 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.