AVA 4 Release Candidate 1

AVA 4 is nearly done! We’re not expecting major breaking changes, so barring any bugs or other surprises this should be it.

As always with pre-releases though you’re best-off installing an exact version:

npm install -D -E ava@next

The cool new stuff 🆒

Worker threads 🧑‍💼

By default, test files are now run in worker threads! Huge thanks to @dnlup for landing this.

Test files should run a little quicker, since it's easier to spin up a worker thread than a child process. You can use --no-worker-threads on the command line, or workerThreads: false in your AVA configuration, to fall back to using child processes.

Shared workers are no longer experimental 🎊

Shared workers are no longer experimental. This is a powerful feature that loads a program in a worker thread in AVA's main process and then communicate with code running in the test workers. This enables your tests to better utilize shared resources during a test run, as well as providing opportunities to set up these resources before tests start (or clean them up after).

When you use watch mode, shared workers remain loaded across runs.

Improved test selection 🤳

AVA selects test files based on your package.json or ava.config.* configuration files. When used on the CLI you can then provide patterns to select a subset of these files.

You can now pass a folder and AVA will select the test files contained therein. Or you can provide a specific JavaScript file and AVA will run it even if it wasn’t selected by your configuration.

If AVA finds files based on the configuration, but none of those were selected to the CLI arguments, it now prints a warning.

Better monorepo support 🚝

AVA now looks for ava.config.* files in parent directories, until it finds a directory with a .git directory (or file). This lets you specify AVA configuration at the top of your monorepo and still run AVA from within each package.

New snapshot format 📸

@ninevra has worked tirelessly on landing a new snapshot format. It contains all information necessary to regenerate the report file. This allows for snapshots to be updated even if tests or assertions are skipped.

Previously failing test files run first 🏃

AVA now records which test files failed in the previous run. It then prioritizes testing these files when you run AVA again. Thanks @bunysae!

ESM support 🤾

AVA 4 comes with full ES module support. Both ESM and CJS entrypoints are provided so that you can use it no matter how you manage your project.

The ava.config.js file is now treated as CJS or ESM depending on module type configured in the package.json file. ava.config.mjs is now supported.

If you use JavaScript files with non-standard extensions you can configure AVA to import them.

Note that dependency tracking in watch mode does not yet work with ES modules.

Dedicated macro factory with type inference 🏭

test.macro() returns an object that can be used with
test() and hooks. The t.context type is inherited from test. When used with TypeScript this gives much better type inference.

Like with AVA 3, regular functions that also have a title property
that is a string-returning function are supported. However the type checking won’t be as good.

Source maps 🗺

AVA now uses the source map support that’s built in to Node.js itself. This should give better stack traces. However we’re not sure yet what happens if you load a program that automatically modifies stack traces.

Line number selection (where npx ava test.js:5 runs the test at line 5) now uses source maps and so should work better with TypeScript files.

Assertions as type guards 💂

Most assertions now return a boolean indicating whether they passed. If you use AVA with TypeScript, you can use this as a type guard. Thanks @jmarkham828!

(This is not supported for t.snapshot() and the "throws" assertions.)

Breaking changes 💥

AVA 4 requires at least Node.js 12.22, 14.17, 16.4 or 17. Node.js 10 is no longer supported.

If installed globally, AVA will no longer use any locally installed version. Install locally and run with npx ava instead. When running test files from another project that also has AVA installed, those test files will now fail to run (because they'll try and use that other AVA version).

Ecosystem 🏞

• Support for @ava/babel has been removed. We haven’t seen enough contributions to that package to recommend it for AVA 4. We’d be open to reinstating it in the future (just as we’d be open to support any other compilation provider).
• As a consequence, “enhanced assertions” are no longer available.
• AVA 4 requires avajs/typescript@1.1 or newer.
• Support for the esm package has been removed.

Configuration 🗒

• ava.config.js now follows the module type configured in package.json.
• ava.config.* files may be found that are outside your project directory.

Tests and assertions 🥼

• By default test files execute in worker threads, not child processes.
• test.meta.file and test.meta.snapshotDirectory are now file URL strings.
• Whitespace in test titles is now normalized. This could result in two tests being treated as having the same title, even though they are different in code. Thanks @KillyMXI!
• test() and t.try() no longer take an array of test implementations. Use a loop instead.
• The t.throws() and t.throwAsync() assertions can no longer be called with a null value for the expectations argument.
• test.cb() and t.end() have been removed. Use async functions and util.promisify() instead.
• t.teardown() now executes in last-in-first-out order.

Snapshots 📸

• Snapshots recorded using earlier AVA versions are no longer recognized. Run npx ava -u to rebuild your snapshots after upgrading.
• Snapshots no longer recognize React elements, instead we want to provide this functionality through a plugin interface
• t.snapshot() no longer works in hooks.
• t.snapshot() no longer takes an options argument allowing you to customize the snapshot ID.

TypeScript 🪛

• The instanceOf expectation of t.throws() and t.throwsAsync() assertions must now be an Error constructor.
• You’re expected to use test.macro() when declaring macros.
• Implementation arguments now default to unknown.
• Types have been renamed. Meta replaces MetaInterface, other types with Interface suffixes now use the Fn suffix. There may be some other changes too. 4b4b2f6
• t.throws() and t.throwsAsync() return undefined when the assertion fails. The type definition now matches this behavior.
• Our TypeScript definitions are now tested against TypeScript 4.4

Other changes 🤓

• We’ve removed the non-verbose reporter because it proved too hard to maintain two subtly different reporter outputs. We’d really like to rewrite the reporter.
• AVA's configuration files may now export promises or asynchronous factory methods.
• The --config argument may now point to a file that is not alongside the package.json file.
• When you use t.timeout(), AVA itself won’t time out until your test does. Thanks @OhYash!
• Multi-line snapshot labels now render correctly in Markdown. Thanks @KillyMXI!
• The reporters now clean up .test and .spec extensions from file names, as well as test- prefixes.
• Watch mode is better at detecting changes to snapshots and not rerunning tests.

New Contributors

• @Fem-Fem made their first contribution in #2750
• @OhYash made their first contribution in #2758
• @KillyMXI made their first contribution in #2773
• @mcecode made their first contribution in #2794
• @duncanfinney made their first contribution in #2820
• @asaid-0 made their first contribution in #2788
• @bompus made their first contribution in #2843
• @StefanoA1 made their first contribution in #2849
• @live627 made their first contribution in #2851
• @alessandroasm made their first contribution in #2863
• @eltociear made their first contribution in #2870
• @hamidbae made their first contribution in #2878

Full changelog since Alpha 2: v4.0.0-alpha.2...v4.0.0-rc.1

4.0.0 Alpha 2

This is the second (pre)release of AVA 4 🎊 Please read the release notes for Alpha 1.

Breaking changes 💥

• Shared workers are available only in worker threads, not child processes. Thanks @dnlup! bdf2cf0
• If installed globally, AVA will no longer use any locally installed version. Install locally and run with npx ava instead 1ee1e82
• When running test files from another project that also has AVA installed, those test files will now fail to run (because they'll try and use that other AVA version) cc4e622

Other changes 🤓

• Remove --preserve-symlink and npm link detection eef1a55
• Correctly resolve ESLint plugin helper worker path 000c42e
• Time out ESLint config resolution after 10 seconds 3aac5e8
• Explicit and separate CJS and ESM entrypoints 5e08444

v4.0.0-alpha.1...v4.0.0-alpha.2

4.0.0 Alpha 1

This is the first (pre)release of AVA 4 🎊 There's some great new features, some cleanup of old interfaces, and some other smaller-but-still-breaking changes.

You can install the latest AVA 4 prerelease using:

npm install -D -E ava@next

The cool new stuff

Worker threads 🧑‍💼

By default, test files are now run in worker threads! Huge thanks to @dnlup for landing this. 0e5cc7d

Test files should run a little quicker, since it's easier to spin up a worker thread than a child process. You can use --no-worker-threads on the command line, or workerThreads: false in your AVA configuration, to fall back to using child processes.

New snapshot format 📸

@ninevra has worked tirelessly on landing a new snapshot format. It contains all information necessary to regenerate the report file. This allows for snapshots to be updated even if tests or assertions are skipped. 14ec281

Asynchronous config loading & ESM support 🤾

AVA's configuration files may now export promises or asynchronous factory methods. The ava.config.js file is now treated as CJS or ESM depending on module type configured in the package.json file. ava.config.mjs is now supported. f7cb1c7 c7b7820

Previously failing test files run first 🏃

AVA now records which test files failed in the previous run. It then prioritizes testing these files when you run AVA again. Thanks @bunysae! d742672

Assertions as type guards 💂

Most assertions now return a boolean indicating whether they passed. If you use AVA with TypeScript, you can use this as a type guard. Thanks @jmarkham828! 72a4e2f 5eea608

(This is not supported for t.snapshot() and the "throws" assertions.)

The breaking changes 💥

• AVA 4 requires Node.js 12.20, 14.15 or 15. Node.js 10 is no longer supported 5dd22c9
• By default test files execute in worker threads, not child processes 0e5cc7d
• ava.config.js now follows the module type configured in package.json f7cb1c7 c7b7820
• Snapshots recorded using earlier AVA versions are no longer recognized. Run npx ava -u to rebuild your snapshots after upgrading 14ec281
• Snapshots no longer recognize React elements, instead we want to provide this functionality through a plugin interface 26999c4
• t.snapshot() no longer works in hooks bcb750c
• t.snapshot() no longer takes an options argument allowing you to customize the snapshot ID d8b1e89
• test.cb() and t.end() have been removed. Use async functions and util.promisify() instead.
• The t.throws() and t.throwAsync() assertions can no longer be called with a null value for the expectations argument 7f64f5c
• t.teardown() now executes in last-in-first-out order dc4483f
• Support for the esm package has been removed 2011b92
• Our TypeScript definitions are now tested against TypeScript 4.2 6429581 9cedc97
• A whole host of experimental features have become default, and can no longer be opted into.

Other changes 🗒

Our TypeScript recipe has been updated with ts-node and ESM instructions. Thanks @mesqueeb! a079152

We'd also like to thank @kiancross, @papb and @jerrygreen.

v3.15.0...v4.0.0-alpha.1

3.15.0

Automatic snapshot file removal

When you stop using snapshots in a test file, the next time you run ava --update-snapshots we'll remove the left-over snapshot files. Thanks @ninevra! 4f093ab

TAP improvements

@tymfear has been on a roll improving our TAP reporter. t.log() output is now compliant with the spec 99ab93a. Tests that did not run due to timeouts are now reported 98595da.

Next-generation configuration

AVA 4 will add full support for ESM configuration files as well as allowing you to have asynchronous factory functions a2f2614. If you're using Node.js 12 or later you can opt-in to these features in AVA 3 by enabling the nextGenConfig experiment. Say in an ava.config.mjs file:

export default {
	nonSemVerExperiments: {
		nextGenConfig: true
	},
	files: ['unit-tests/**/*]
};

This also allows you to pass an .mjs file using the --config argument.

With this experiment enabled, AVA will no longer have special treatment for ava.config.js files. Instead AVA follows Node.js' behavior, so if you've set "type": "module" you must use ESM, and otherwise you must use CommonJS.

You mustn't have an ava.config.mjs file next to an ava.config.js or ava.config.cjs file.

---

See v3.14.0...v3.15.0 for all changes.

3.14.0

Snapshot ordering

With this release, snapshot files are now ordered based on test declaration, not completion. This makes it easier to compare the human-readable reports to your test file, and also stops the .snap from changing when the reports themselves don't. You'll want to rebuild snapshots after upgrading to this release to isolate any changes. Thanks @ninevra! e66b54c

Shared workers

We’ve been working on making AVA more extensible. One major step on this path is our new shared worker support: run code in the main process, communicate with test workers and influence execution. Find out more in our shared workers recipe.

---

See v3.13.0...v3.14.0 for all changes.

3.13.0

• t.passed can now be used in tests and teardown functions. Thanks @tymfear! 900dc6d
• In AVA 4, you'll no longer be able to pass null as the expectation for t.throws() & t.throwsAsync(). You can opt in to this early by enabling the disableNullExpectations experiment. Thanks @JSimoni42! f328a69
• The Enzyme recipe has been updated. Thanks @jonathansamines! db5d2c3
• The TypeScript recipe has been updated. Thanks @SephReed! a3379fa

See v3.12.1...v3.13.0 for all changes.

3.12.1

Configure how AVA loads test files

Normally, AVA loads all files as CommonJS, except for mjs files and if you've configured "type": "module" in your package.json.

As an experiment, you can now configure how AVA loads other file extensions. This is useful if you want to use Node.js' experimental loaders feature. Read more in our documentation. Thank you @macarie for working on this! 5c9dbb9

Comparison bugfix

There was a bug in our comparison library which meant that negative-index properties on lists were not compared. This was fixed in a patch release, which will definitely be installed when you install AVA 3.12. Your tests may have been passing, even though they should have been failing. They'll fail now. Snapshots may also be different, causing tests to fail.

All changes

See v3.11.1...v3.12.1 for all changes.

Thank you @anthumchris for making sure our ESM example used ESM syntax (20bc781).

3.11.1

This release fixes corrupted output of the default reporter when test or program code writes to standard out. 5ddc9fd

Also, thanks to @jonathansamines we've taken another step to using AVA to test AVA. 1150991

See v3.11.0...v3.11.1 for all changes.

3.11.0

New t.like() assertion

Thanks to @futpib we now have a t.like() assertion 19c4f35:

In the following example, the map property of value must be deeply equal to that of selector. However nested.qux is ignored, because it's not in selector.

t.like({
	map: new Map([['foo', 'bar']]),
	nested: {
		baz: 'thud',
		qux: 'quux'
	}
}, {
	map: new Map([['foo', 'bar']]),
	nested: {
		baz: 'thud',
	}
})

Read more in the t.like() assertion documentation.

This assertion was previously introduced as an experiment.

VSCode 1.47 debugging improvements

You can now debug tests using the new JavaScript Debug Terminal in VSCode 1.47. We've updated our debugging recipe accordingly. Thank you @connor4312 for the documentation updates and your work on VSCode! bc39bcc

All changes

See v3.10.1...v3.11.0 for all changes.

3.10.1

It's time for another AVA release 🎉

Restricting when you can update snapshots

When executing a subset of tests, through --match or or .only() or .skip(), you can no longer also update snapshots. This prevents you from accidentally deleting snapshots. Thank you @bunysae for putting this together. f72fab4

If you are skipping a test that you can't immediately fix, but you still need to update snapshots, use .failing() instead.

Support for message strings in t.timeout() calls

Thanks to @jonathansamines you can now provide a message string when using t.timeout(). This can be useful if your test depends on some other setup that may not have been completed: ca8ea45

test('foo', t => {
	t.timeout(100, 'make sure database has started');
	// Write your assertions here
});

t.try() does not work in hooks

t.try() has never worked in hooks, but thanks to @okyantoro it now fails properly instead of crashing. d01db61

t.snapshot() does not really work in hooks either

t.snapshot() sort of works in hooks, but we'll be removing this in AVA 4. You can opt in to this behavior by enabling the disableSnapshotsInHooks experiment. Again thank you @okyantoro d01db61.

Fixed TypeScript definition for t.like()

The experimental t.like() assertion should now work better with TypeScript.

All changes

See v3.9.0...v3.10.1 for all changes.