Package detail

fast-check

dubzzz8.1mMIT3.23.2

Property based testing framework for JavaScript (like QuickCheck)

property-based testing, end-to-end testing, unit testing, testing, quickcheck, jscheck, jsverify, faker, fuzzer, fuzz, jest

readme

Property based testing framework for JavaScript/TypeScript

Getting started

Hands-on tutorial and definition of Property Based Testing: 🏁 see tutorial. Or directly try it online on our pre-configured CodeSandbox.

Property based testing frameworks check the truthfulness of properties. A property is a statement like: for all (x, y, ...) such that precondition(x, y, ...) holds predicate(x, y, ...) is true.

Install the module with: yarn add fast-check --dev or npm install fast-check --save-dev

Example of integration in mocha:

import fc from 'fast-check';

// Code under test
const contains = (text, pattern) => text.indexOf(pattern) >= 0;

// Properties
describe('properties', () => {
  // string text always contains itself
  it('should always contain itself', () => {
    fc.assert(fc.property(fc.string(), (text) => contains(text, text)));
  });
  // string a + b + c always contains b, whatever the values of a, b and c
  it('should always contain its substrings', () => {
    fc.assert(
      fc.property(fc.string(), fc.string(), fc.string(), (a, b, c) => {
        // Alternatively: no return statement and direct usage of expect or assert
        return contains(a + b + c, b);
      }),
    );
  });
});

In case of failure, the test raises a red flag. Its output should help you to diagnose what went wrong in your implementation. Example with a failing implementation of contain:

1) should always contain its substrings
    Error: Property failed after 1 tests (seed: 1527422598337, path: 0:0): ["","",""]
    Shrunk 1 time(s)
    Got error: Property failed by returning false

    Hint: Enable verbose mode in order to have the list of all failing values encountered during the run

Integration with other test frameworks: ava, jasmine, jest, mocha and tape.

More examples: simple examples, fuzzing and against various algorithms.

Useful documentations:

Why should I migrate to fast-check?

fast-check has initially been designed in an attempt to cope with limitations I encountered while using other property based testing frameworks designed for JavaScript:

Types: strong and up-to-date types - thanks to TypeScript
Extendable: easy map method to derive existing arbitraries while keeping shrink [more] - some frameworks ask the user to provide both a->b and b->a mappings in order to keep a shrinker
Extendable: kind of flatMap-operation called chain [more] - able to bind the output of an arbitrary as input of another one while keeping the shrink working
Extendable: precondition checks with fc.pre(...) [more] - filtering invalid entries can be done directly inside the check function if needed
Extendable: easily switch from fake data in tests to property based with fc.gen() [more] - generate random values within your predicates
Smart: ability to shrink on fc.oneof [more] - surprisingly some frameworks don't
Smart: biased by default - by default it generates both small and large values, making it easier to dig into counterexamples without having to tweak a size parameter manually
Debug: verbose mode [more][tutorial] - easier troubleshooting with verbose mode enabled
Debug: replay directly on the minimal counterexample [tutorial] - no need to replay the whole sequence, you get directly the counterexample
Debug: custom examples in addition of generated ones [more] - no need to duplicate the code to play the property on custom examples
Debug: logger per predicate run [more] - simplify your troubleshoot with fc.context and its logging feature
Unique: model based approach [more][article] - use the power of property based testing to test UI, APIs or state machines
Unique: detect race conditions in your code [more][tutorial] - shuffle the way your promises and async calls resolve using the power of property based testing to detect races
Unique: simplify user definable corner cases [more] - simplify bug resolution by asking fast-check if it can find an even simpler corner case

For more details, refer to the documentation in the links above.

Trusted

fast-check has been trusted for years by big projects like: jest, jasmine, fp-ts, io-ts, ramda, js-yaml, query-string...

Powerful

It also proved useful in finding bugs among major open source projects such as jest, query-string... and many others.

Compatibility

Here are the minimal requirements to use fast-check properly without any polyfills:

fast-check	node	ECMAScript version	TypeScript (optional)
3.x	≥8⁽¹⁾	ES2017	≥4.1⁽²⁾
2.x	≥8⁽¹⁾	ES2017	≥3.2⁽³⁾
1.x	≥0.12⁽¹⁾	ES3	≥3.0⁽³⁾

<summary>More details...</summary>

Except for features that cannot be polyfilled - such as bigint-related ones - all the capabilities of fast-check should be usable given you use at least the minimal recommended version of node associated to your major of fast-check.
Require either lib or target ≥ ES2020 or @types/node to be installed.
Require either lib or target ≥ ES2015 or @types/node to be installed.

ReScript bindings

Bindings to use fast-check in ReScript are available in package rescript-fast-check. They are maintained by @TheSpyder as an external project.

Contributors ✨

Thanks goes to these wonderful people (emoji key):

_{Nicolas DUBIEN} 💻 📖 ⚠️ 🚇 🎨 🚧	_{Aaron Elligsen} 💻 📖 ⚠️	_{Will Heslam} 📖	_kazchimo 💻 📖	_{Brandon Chinn} 💻 📖	_{Irakli Safareli} 📖	_{Andrew Herron} 📖 🔌
_{Eric Crosson} 📖 💻	_burrscurr 📖	_{JC (Jonathan Chen)} 📖	_{Larry Botha} 📖 💻 ⚠️	_{Roman Gusev} 📖	_{Tim Wisniewski} 📖	_{Brais Piñeiro} 💻 ⚠️
_{Renaud-Pierre Bordes} 🎨	_{Jemma Nelson} 📖	_{John Haugeland} 📖	_{Trey Davis} 🎨	_{Leon Si} 📖	_{Gorgi Kosev} 🚇	_mayconsacht 💻
_{Simon Friis Vindum} 💻 ⚠️	_{Richard Gibson} 📖	_{Alan Harper} 📖	_{Makien Osman} 💻	_{David Sommerich} 💻 ⚠️	_{Diego Pedro} 💻 ⚠️	_{Borui Gu} 📖
_{Brian Donovan} 📖	_volrk 💻 📖 ⚠️	_tinydylan 💻 ⚠️	_{Caleb Jasik} 📖	_{Rulai Hu} 📖	_{Afonso Jorge Ramos} 📖	_{Tom Jenkinson} 📖
_phormio 📖	_{Giovanni Gonzaga} 💻 ⚠️	_{Tomas Carnecky} 💻	_{Kirill Romanov} 💻 📖 ⚠️	_{Giovanny González} 📖	_{Mark Kulube} 🚇	_{Peter Hamilton} 💻
_{Chinedu Ozodi} 📖	_{Gunar Gessner} 📖	_{Christian Batchelor} ⚠️	_{Tomer Aberbach} 💻 📖 ⚠️	_0xflotus 📖	_{Ryan Leonard} 💻 📖 ⚠️	_{Jason Dreyzehner} 💻 ⚠️
_{Matin Zadeh Dolatabad} 💻	_{Juan Julián Merelo Guervós} 📖	_{Simen Bekkhus} 📖	_{Tarjei Skjærset} 📖	_{Denis Gorbachev} 📖	_{Trevor McCauley} 📖	_{Grant Kiely} 📖
_{Attila Večerek} 💻 📖 ⚠️	_{Zach Bjornson} 💻 📖	_{Bennett Perkins} 📖	_{Alexandre Oger} 📖	_{ej shafran} 📖	_{Niklas Gruhn} 💻	_{Patrick Roza} 💻
_{Cindy Wu} 📖	_Noah 📖	_{James Vaughan} 📖

This project follows the all-contributors specification. Contributions of any kind welcome! Become one of them

Sponsors 💸

Many individuals and companies offer their financial support to the project, a huge thanks to all of them too 💓

You can also become one of them by contributing via GitHub Sponsors or OpenCollective.

changelog

3.23.2

Increased resiliency to poisoning [Code][Diff]

Fixes

(PR#5469) Bug: Make subarray a bit more resilient to poisoning
(PR#5468) Bug: Make stringify a bit more resilient to poisoning
(PR#5515) Bug: Make depth retrieval more resilient to poisoning
(PR#5516) Bug: Make mapToConstant a bit more resilient to poisoning
(PR#5517) Bug: Make run details printer a bit more resilient to poisoning
(PR#5518) Bug: Make gen a bit more resilient to poisoning
(PR#5456) CI: Allow Bluesky calls from the blog
(PR#5457) CI: Add Bluesky CDN as trustable source for images
(PR#5410) Doc: Release note for 3.23.0
(PR#5413) Doc: Update social links on footer
(PR#5414) Doc: Drop Twitter badge from README
(PR#5415) Doc: Add link to bluesky account in the header of the doc
(PR#5453) Doc: AdventOfPBT event Day 1
(PR#5454) Doc: Saving Christmas with nroken playground
(PR#5455) Doc: Add links towards Bluesky from the AdventOfPBT
(PR#5460) Doc: Advent Of PBT, day 2
(PR#5461) Doc: Add linkt towards Bluesky comments
(PR#5464) Doc: Add quick code snippet directly from the documentation
(PR#5465) Doc: Quick CTA to our Advent of PBT event
(PR#5467) Doc: Single line success message for the Advent of PBT
(PR#5470) Doc: Notify fast-check.dev account
(PR#5471) Doc: Advent of PBT, day 3
(PR#5472) Doc: Add comments section on Advent of PBT, Day 3
(PR#5474) Doc: Advent of PBT, day 4
(PR#5477) Doc: Add comments section on Advent of PBT, Day 4
(PR#5479) Doc: Advent of PBT Day 5
(PR#5480) Doc: Advent of PBT Day 5, link to comments on Bluesky
(PR#5481) Doc: Do not send new success pixels when advent solved once
(PR#5482) Doc: Add a counter showing the number of times the puzzle got solved
(PR#5489) Doc: Advent Of PBT, Day 6
(PR#5490) Doc: Advent of PBT, comments on Day 6
(PR#5493) Doc: Fix playground code of Day 6
(PR#5495) Doc: Advent of PBT Day 7
(PR#5496) Doc: Advent of PBT Day 7, comments section
(PR#5497) Doc: Advent of PBT Day 8
(PR#5498) Doc: Advent of PBT Day 8, comments section
(PR#5501) Doc: Drop buggy "solved times" at the end of each advent
(PR#5500) Doc: Advent of PBT Day 9
(PR#5503) Doc: Add back buggy "solved times" at the end of each advent
(PR#5505) Doc: Advent of PBT Day 10
(PR#5510) Doc: Advent Of PBT Day 10, comments section
(PR#5508) Doc: Advent Of PBT Day 11
(PR#5507) Doc: Advent Of PBT Day 12
(PR#5509) Doc: Advent Of PBT Day 13
(PR#5523) Doc: Advent of PBT add comments sections on days 11 to 13

3.23.1

Faster instantiation of internet-related arbitraries [Code][Diff]

Fixes

(PR#5402) Performance: Faster instantiation of internet-related arbitraries

3.23.0

Extend usages of string-units and increased performance [Code][Diff]

Features

(PR#5366) Add support for string-unit on object/anything arbitrary
(PR#5367) Add support for string-unit on json arbitrary
(PR#5390) Add back strong unmapping capabilities to string

Fixes

(PR#5327) Bug: Resist even more to external poisoning for string
(PR#5368) Bug: Better support for poisoning on stringMatching
(PR#5344) CI: Adapt some tests for Node v23
(PR#5346) CI: Drop usages of it.concurrent due to Node 23 failing
(PR#5363) CI: Move to Vitest for examples/
(PR#5391) CI: Preview builds using pkg.pr.new
(PR#5392) CI: Connect custom templates to pkg.pr.new previews
(PR#5394) CI: Install dependencies before building changesets
(PR#5396) CI: Proper commit name on changelogs
(PR#5393) Clean: Drop unused examples/jest.setup.js
(PR#5249) Doc: Release note for fast-check 3.22.0
(PR#5369) Doc: Typo fix in model-based-testing.md
(PR#5370) Doc: Add new contributor jamesbvaughan
(PR#5383) Doc: Properly indent code snippets for the documentation
(PR#5372) Performance: Faster canShrinkWithoutContext for constants
(PR#5386) Performance: Faster generate process for mapToConstant
(PR#5387) Performance: Faster tokenizer of strings
(PR#5388) Performance: Faster initialization of string with faster slices
(PR#5389) Performance: Faster initialization of string with pre-cached slices
(PR#5371) Test: Add extra set of tests for constant*

3.22.0

Graphemes support on fc.string [Code][Diff]

Features

(PR#5222) Support for grapheme on fc.string
(PR#5233) Mark as deprecated most of char and string arbitraries
(PR#5238) Deprecate bigInt's alternatives

Fixes

(PR#5237) CI: Drop TypeScript rc release channel
(PR#5241) CI: Move to changeset
(PR#5199) Doc: Publish release note for 3.21.0
(PR#5240) Doc: Better string's deprecation note in documentation
(PR#5203) Refactor: Add missing types on exported

3.21.0

Support customisable versions on uuid [Code][Diff]

Features

(PR#5172) Support UUID versions [1-15] on uuidV
(PR#5189) Deprecate uuidV in favor of uuid
(PR#5188) Customize versions directly from uuid

Fixes

(PR#5190) CI: Support npm publish on other tags
(PR#5124) Doc: Publish release note for 3.20.0
(PR#5137) Doc: Add missing options in the documentation for float and double
(PR#5142) Doc: Better width for stargazer badge in the documentation
(PR#5143) Doc: Document Faker integration
(PR#5144) Doc: Add support us page in our documentation

3.20.0

New arbitraries to alter shrinking capabilities [Code][Diff]

Features

(PR#5047) Introduce new fc.noShrink arbitrary
(PR#5050) Introduce new fc.noBias arbitrary
(PR#5006) Add ability to limit shrink path
(PR#5112) Simplify limitShrink before releasing

Fixes

(PR#5013) CI: Drop verbosity flag at unpack step in CI
(PR#5074) CI: Check types with multiple TypeScript
(PR#5015) Doc: Release note for 3.19.0
(PR#5016) Doc: Fix typo in the PR template
(PR#4858) Doc: Update Getting Started section in docs
(PR#5035) Doc: Remove duplicate paragraph in your-first-race-condition-test.mdx
(PR#5048) Doc: Add new contributors cindywu and nmay231
(PR#5097) Doc: Add warning on noShrink
(PR#5121) Doc: Document integration with other test runners

3.19.0

New options to generate unicode strings on objects [Code][Diff]

Features

(PR#5010) Add option to generate unicode values in object
(PR#5011) Add option to generate unicode values in json

Fixes

(PR#4981) Bug: Better interrupt between multiple versions
(PR#4984) CI: Rework issue template
(PR#4941) Doc: Publish release note for 3.18.0
(PR#4982) Script: Shorter bump command

3.18.0

New options for floating point arbitraries [Code][Diff]

Features

(PR#4917) Add option to produce non-integer on double
(PR#4923) Add option to produce non-integer on float
(PR#4935) Produce "//" in web paths

Fixes

(PR#4924) CI: Enable more advanced TS flags
(PR#4925) CI: Explicitly test against Node 22
(PR#4926) CI: Stabilize tests of double on small ranges
(PR#4921) Performance: More optimal noInteger on double
(PR#4933) Script: Switch on more eslint rules
(PR#4922) Test: Cover noInteger on double via integration layers

3.17.2

Directly reference the official documentation from NPM [Code][Diff]

Fixes

(PR#4853) CI: Build doc with full git history
(PR#4872) CI: Stop caching Jest on CI
(PR#4852) Doc: Show last update time on doc
(PR#4851) Doc: Add last modified date to sitemap
(PR#4868) Doc: Enhance SEO for homepage
(PR#4888) Doc: Add tutorial for PBT with Jest
(PR#4901) Doc: Use official doc for npm homepage
(PR#4866) Test: Safer rewrite of Poisoning E2E
(PR#4871) Test: Move tests to Vitest
(PR#4863) Test: Explicitely import from Vitest
(PR#4873) Test: Move to v8 for coverage
(PR#4875) Test: Better mock/spy cleaning

3.17.1

Better interrupt CJS/MJS regarding types [Code][Diff]

Fixes

(PR#4842) Bug: Fix dual-packages hazard and types incompatibility
(PR#4836) Doc: Release note for 3.17.0
(PR#4844) Doc: Add new contributor patroza

3.17.0

Allow access to some internals details linked to the underlying random generator [Code][Diff]

Features

(PR#4817) Expose internal state of the PRNG from Random

Fixes

(PR#4781) Doc: Official release note of 3.16.0
(PR#4799) Doc: Add more links in the footer
(PR#4800) Doc: Better colors for footer and dark mode

3.16.0

Type assert on assertions linked to fc.pre [Code][Diff]

Features

(PR#4709) Make fc.pre an assertion function

Fixes

(PR#4736) Bug: Wrong logo ratio on small screen
(PR#4747) CI: Deploy website on Netlify
(PR#4751) CI: Drop configuration of GitHub Pages
(PR#4756) CI: Make CI fail on invalid deploy
(PR#4776) CI: Drop Google Analytics
(PR#4769) Clean: Drop legacy patch on React 17
(PR#4677) Doc: Add jsonwebtoken to track record
(PR#4712) Doc: Fix console errors of website
(PR#4713) Doc: Add extra spacing on top of CTA
(PR#4730) Doc: Optimize image assets on homepage
(PR#4732) Doc: Optimize SVG assets
(PR#4735) Doc: Less layout shift with proper sizes
(PR#4750) Doc: Add link to Netlify
(PR#4754) Doc: Better assets on the homepage of the website
(PR#4768) Doc: Add new contributors ej-shafran and gruhn
(PR#4771) Doc: Blog post for 3.15.0
(PR#4753) Security: Configure CSP for fast-check.dev
(PR#4761) Security: Enforce Content-Security-Policy on our website
(PR#4772) Security: Relax CSP policy to support Algolia

3.15.1

Prepare the monorepo for ESM build-chain [Code][Diff]

Fixes

(PR#4591) CI: Move build chain to ESM for root of monorepo
(PR#4598) CI: Add onBrokenAnchors'check on Docusaurus
(PR#4606) CI: Configuration files for VSCode
(PR#4650) CI: Move examples build chain to ESM
(PR#4554) Doc: Add idonttrustlikethat-fast-check in ecosystem.md
(PR#4563) Doc: Add new contributor nielk
(PR#4669) Doc: Add @effect/schema in ecosystem
(PR#4665) Test: Fix isCorrect check on double
(PR#4666) Test: Stabilize flaky URL-related test

3.15.0

Add support for depthIdentifier to dictionary [Code][Diff]

Features

(PR#4548) Add support for depthIdentifier to dictionary

Fixes

(PR#4502) Bug: Also produce null-prototype at root level of generated object when requested to
(PR#4481) CI: Migrate configuration of Docusaurus to TS
(PR#4463) Doc: Blog post for 3.14.0
(PR#4464) Doc: Prefer import notation over require for README
(PR#4482) Doc: Rework section on waitAll in the tutorial
(PR#4477) Doc: Fix typo in date.md
(PR#4494) Doc: Add new contributor bennettp123
(PR#4541) Refactor: Rely on dictionary for object instead of inlined reimplementation
(PR#4469) Test: More stable snapshot tests on stack traces
(PR#4470) Test: Add cause flag onto snapshot tests checking stack traces
(PR#4478) Test: Better snapshots tests implying stacktraces
(PR#4483) Test: Wrap async no-regression snapshots within a sanitizer for stacktraces

3.14.0

Lighter import with less internals to load [Code][Diff]

Features

(PR#4426) Prefer "import type" over raw "import"

Fixes

(PR#4364) CI: Toggle more immutable on yarn
(PR#4369) CI: Do not override existing on untar
(PR#4372) CI: REVERT Do not override existing on untar
(PR#4371) CI: Mark final check as failed and not skipped
(PR#4375) CI: Attempt to patch untar step
(PR#4378) CI: Attempt to patch untar step
(PR#4380) CI: Add missing but directly called dependencies
(PR#4384) CI: Attempt to patch untar step
(PR#4368) CI: Attempt to switch to pnp linker
(PR#4407) CI: No parallel "git" command
(PR#4419) CI: Prefer "import type" via linter
(PR#4428) CI: Default to Node 20 for CI
(PR#4441) CI: Add support for PnP on VSCode
(PR#4345) Performance: Faster replay: drop loose compare
(PR#4381) Test: Import buffer via aliased name

3.13.2

Better reporting for invalid paths [Code][Diff]

Fixes

(PR#4344) Bug: Path wrongly reported when invalid
(PR#4279) CI: Better caching for yarn
(PR#4346) CI: Better yarn caching in CI
(PR#4347) CI: Avoid yarn install on "cache hit"
(PR#4348) CI: Create job to confirm all passed
(PR#4352) CI: Skip install on hot cache (win/mac)
(PR#4299) Doc: Article around Zod vulnerability
(PR#4306) Doc: Fixing a typos in Zod article
(PR#4307) Doc: Add missing robots.txt
(PR#4356) Doc: Better document limitations of gen
(PR#4338) Script: Faster tests execution with babel
(PR#4270) Test: Check tsc import and types of bundled package
(PR#4271) Test: Typecheck ESM bundle correctly
(PR#4269) Test: Rework checks against legacy node

3.13.1

Fix typings for node native esm [Code][Diff]

Fixes

(PR#4261) Bug: Fix typings for node native esm
(PR#4230) Doc: Release note for 3.13.0
(PR#4240) Doc: Some tips on prototype pollution
(PR#4246) Doc: Fix typo in "Detect prototype pollution automatically"

3.13.0

New options for date, record and dictionary [Code][Diff]

Features

(PR#4197) Add support for "Invalid Date" in date
(PR#4203) Deprecate withDeletedKeys on record
(PR#4204) Support null-proto in dictionary
(PR#4205) Support null-proto in record

Fixes

(PR#4207) Bug: Better poisoning resiliency for dictionary
(PR#4194) CI: Add some more details onto the PWA
(PR#4211) CI: Rework broken test on date
(PR#4212) CI: Rework broken test on date (retry)
(PR#4214) CI: Rework another broken test on date
(PR#4186) Doc: Document our approach to dual package
(PR#4187) Doc: Expose website as PWA too
(PR#4190) Move: Move the manifest in /static
(PR#4206) Refactor: Re-use null-proto helpers of dictionary on anything
(PR#4189) Test: Drop Node 14.x from the test-chain

3.12.1

Better support for types on ESM targets [Code][Diff]

Fixes

(PR#4172) Bug: Better declare ESM's types
(PR#4177) Bug: Replace macros in published esm types
(PR#4156) CI: Stop formatting built website
(PR#4155) CI: Add TypeScript checks on website
(PR#4171) CI: Update Devcontainer settings
(PR#4181) CI: Add exempted labels for stale bot
(PR#4136) Clean: Drop dependency @testing-library/jest-dom
(PR#4107) Doc: What's new article for fast-check 3.12.0
(PR#4118) Doc: Drop raw bench results from release note
(PR#4117) Test: Stabilize test related to NaN in exclusive mode
(PR#4033) Tooling: Update formatting

3.12.0

Faster float, double and ulid and excluded min/max [Code][Diff]

Features

(PR#4100) Support excluded min/max in double
(PR#4105) Support excluded min/max in float

Fixes

(PR#4094) Bug: Stop unwrapping ulid we cannot build
(PR#4095) Bug: Be resilient to poisoning with ulid
(PR#4041) CI: Ensure we use latest node in range
(PR#4062) CI: Update devcontainer configuration
(PR#4065) CI: Better configuration for renovate
(PR#4068) CI: Refine configuration of renovate
(PR#4073) CI: New attempt to configure renovate
(PR#4075) CI: Configure renovate to bump non-package
(PR#4078) CI: Disable nodenv bumps on renovate
(PR#4080) CI: Stop bumping node via renovate
(PR#4040) Doc: Prepare release note for 3.11.0
(PR#4087) Doc: Add new contributor zbjornson
(PR#4059) Performance: Faster decomposeFloat/Double
(PR#4088) Performance: Drop some unneeded allocs in ulid
(PR#4091) Performance: Faster unmap for ulid
(PR#4092) Performance: Faster generation of ulid
(PR#4098) Performance: Faster ulid mapper function
(PR#4039) Script: Add support for more gitmojis

3.11.0

New arbitrary for ulid [Code][Diff]

Features

(PR#4020) Implement arbitrary for ulid

Fixes

(PR#3956) CI: Define code owners
(PR#3961) CI: Fix configuration of CodeQL
(PR#3973) CI: Make changelog workflow able to push
(PR#3975) CI: Add scorecard security workflow
(PR#3991) CI: Properly reference tags in GH Actions
(PR#3993) CI: Configure renovate for security bumps
(PR#3994) CI: Stop ignoring examples in renovate
(PR#3995) CI: Enable some more Scorecard's checks
(PR#4007) CI: Fix CI tests for types against next
(PR#4008) CI: Show vulnerabilities in renovate
(PR#3976) Doc: Add some OpenSSF badges
(PR#4034) Doc: Add new contributor vecerek
(PR#4010) Security: Move dockerfile content to devcontainer
(PR#4000) Security: Drop raw install of npm
(PR#3987) Security: Pin npm version for publish
(PR#3985) Security: Pin image in Dockerfile of devcontainer
(PR#3983) Security: Safer workflows' permissions
(PR#3957) Security: Lock GH-Actions dependencies

3.10.0

New arbitrary generating strings matching the provided regex: stringMatching [Code][Diff]

Features

(PR#3920) Prepare tokenizers for stringMatching
(PR#3921) Introduce stringMatching
(PR#3924) Add support for negate regex
(PR#3925) Explicit ban of unsupported regex flags in stringMatching
(PR#3926) Add support for capturing regexes
(PR#3927) Add support for disjunctions in regexes
(PR#3928) Correctly parse ^ and $ in regex
(PR#3929) Correctly parse numeric backreference
(PR#3930) Correctly parse look{ahead,behind} in regexes
(PR#3932) Support empty disjunctions in regexes
(PR#3933) Add parsing support for \p and \k
(PR#3935) Support generation of strings not constrained by ^ or $
(PR#3938) Support regex flags: d, m and s
(PR#3939) Support unicode regexes

Fixes

(PR#3909) Clean: Drop bundle centric tests
(PR#3902) Doc: Release note page for 3.9.0
(PR#3904) Doc: Fix typo in What's new 3.9.0
(PR#3910) Doc: Lazy load image of sponsors
(PR#3911) Doc: Add alt labels on feature badges
(PR#3912) Doc: Stop lazy images in critical viewport
(PR#3913) Doc: Better a11y on feature badges
(PR#3898) Script: Run publint in strict mode
(PR#3903) Test: Rework race conditions specs in tutorial
(PR#3931) Test: Add some more checks on stringMatching
(PR#3936) Test: Test against more regexes in stringMatching
(PR#3940) Test: Add some more known regexes in our test suite

3.9.0

Finer definition of act to detect race conditions [Code][Diff]

Features

(PR#3889) Add ability to customize act per call
(PR#3890) Add ability to customize act per wait

Fixes

(PR#3892) Bug: Cap timeout values to 0x7fff_ffff

3.8.3

Ensure scheduled models can wait everything needed [Code][Diff]

Fixes

(PR#3887) Bug: Always schedule models until the end
(PR#3880) CI: Stabilize tests on jsonValue
(PR#3876) Clean: Drop legacy documentation
(PR#3875) Doc: First blog post on docusaurus switch

3.8.2

Rework documentation [Code][Diff]

Fixes

(PR#3780) CI: Do not relaunch build on new tag
(PR#3792) CI: Remove parse5 when checking types
(PR#3804) CI: Build documentation with LFS enabled
(PR#3800) Doc: Add "advanced" part of the documentation
(PR#3803) Doc: Update our-first-property-based-test.md: typo, punctuation
(PR#3828) Doc: Fix typos in docs
(PR#3820) Doc: First iteration on race conditions tutorial
(PR#3834) Doc: Rework intro of race condition tutorial
(PR#3836) Doc: Merge category and intro for race condition
(PR#3837) Doc: Replace categories by real pages
(PR#3838) Doc: Add video explaining race condition in UI
(PR#3842) Doc: Note about solving race conditions
(PR#3843) Doc: Better colors for dark theme
(PR#3850) Doc: Points to projects in our ecosystem
(PR#3852) Doc: List some bugs found thanks to fast-check
(PR#3860) Doc: Use GitHub logo instead of label
(PR#3858) Doc: Rework homepage page of fast-check.dev
(PR#3863) Doc: Rework display of the homepage for small screens
(PR#3864) Doc: Properly display the quick nav buttons
(PR#3871) Doc: Update all links to new documentation
(PR#3867) Doc: Create proper images in website/
(PR#3872) Doc: Reference image from LFS in README
(PR#3835) Test: Add tests for snippets in the website

3.8.1

New website for the documentation [Code][Diff]

Fixes

(PR#3723) CI: Switch to docusaurus for the documentation
(PR#3729) CI: Pre-setup devcontainer with GH Actions
(PR#3728) CI: Change gh-pages deploy process
(PR#3732) CI: Move back to github-pages-deploy-action
(PR#3735) CI: Add gtag for analytics
(PR#3744) CI: Drop website build on build:all
(PR#3751) CI: Update baseUrl on the ain documentation
(PR#3754) CI: Drop version from website
(PR#3754) CI: Drop version from website
(PR#3759) CI: Drop the need for a branch on doc
(PR#3775) CI: Publish all packages in one workflow
(PR#3724) Doc: Add fuzz keywords
(PR#3734) Doc: Add search capability to the doc
(PR#3738) Doc: Fix broken links to api-reference
(PR#3745) Doc: Document core building blocks in new documentation
(PR#3750) Doc: More details into tips/larger-entries...
(PR#3753) Doc: Add some more configuration tips in the documentation
(PR#3755) Doc: Update all links to target fast-check.dev
(PR#3757) Doc: Quick a11y pass on the documentation
(PR#3758) Doc: Move missing configuration parts to new doc
(PR#3760) Doc: Link directly to the target page not to 30x ones
(PR#3761) Doc: Fix broken links in new doc
(PR#3774) Security: Attach provenance to the packages
(PR#3719) Script: Ensure proper package definition

3.8.0

Introduce new gen arbitrary [Code][Diff]

Features

(PR#3395) Introduce new gen arbitrary

Fixes

(PR#3706) Doc: Document newly added fc.gen()

3.7.1

Safer declaration of types in package.json [Code][Diff]

Fixes

(PR#3671) Bug: Declare types field first in exports
(PR#3646) Doc: Fix a typo in Runners.md

3.7.0

Better error reports without duplicated messages [Code][Diff]

Features

(PR#3638) Stop repeating the error twice in reports

Fixes

(PR#3637) CI: Update ts-jest configuration files

3.6.3

Fix broken replay based on path [Code][Diff]

Fixes

(PR#3617) Bug: Fix broken replay based on path
(PR#3583) CI: Do not run publish workflow of fast-check for vitest
(PR#3616) CI: Always build against latest node

3.6.2

Still work in fake timer contexts [Code][Diff]

Fixes

(PR#3571) Bug: Resist to fake timers in interruptAfterTimeLimit
(PR#3572) Bug: Resist to fake timers in timeout
(PR#3564) Performance: Drop bailout linked to toss

3.6.1

Some more performance improvements [Code][Diff]

Fixes

(PR#3563) Performance: Mutate rng inplace in tosser

3.6.0

Slightly faster execution of properties [Code][Diff]

Features

(PR#3547) Slightly faster thanks to pure-rand v6
(PR#3552) Do not wrap stream when dropping 0 items
(PR#3551) Faster implementation of internal function runIdToFrequency
(PR#3553) Drop useless internal stream conversions
(PR#3554) Tosser must immediately produce values

Fixes

(PR#3556) CI: Enable sourceMap in unpublished for coverage
(PR#3512) Script: Add --cache option to Prettier
(PR#3523) Script: Initialize default devcontainer
(PR#3524) Script: Install and setup nvs inside Dockerfile

3.5.1

Still work in fake timer contexts [Code][Diff]

Fixes

(PR#3571) Bug: Resist to fake timers in interruptAfterTimeLimit
(PR#3572) Bug: Resist to fake timers in timeout

3.5.0

Interrupt running tasks when interruptAfterTimeLimit exceeded [Code][Diff]

Features

(PR#3507) Interrupt predicates when interruptAfterTimeLimit
(PR#3508) Mark interrupted runs without any success as failures

3.4.0

Better handling of timeout with beforeEach and afterEach [Code][Diff]

Features

(PR#3464) No timeout for beforeEach or afterEach

Fixes

(PR#3428) Bug: Avoid stack overflow during shrinking of tuples
(PR#3432) Bug: Avoid stack overflow during shrinking of arrays
(PR#3354) CI: Ignore version bump checks on publish
(PR#3379) CI: Fix configuration for rollup esm tests
(PR#3394) CI: Limit scope of "All ...bump declared"
(PR#3393) CI: Run tests against Node 18.x
(PR#3446) CI: Drop circular deps for dev topo builds
(PR#3417) Clean: Drop v2 to v3 codemods from the repository
(PR#3351) Doc: Update changelogs following backports
(PR#3458) Doc: Document how to use context in examples
(PR#3476) Doc: Revamp sponsoring section to show GitHub Sponsors
(PR#3473) Funding: Re-order links in funding section
(PR#3427) Refactor: Expose shrinker of tuples internally
(PR#3468) Script: Ensure we don't release workspace-based packages

3.3.0

Expose webPath arbitrary [Code][Diff]

Features

(PR#3299) Explicitly declare typings for constraints on date
(PR#3300) Expose an url path builder called webPath

Fixes

(PR#3328) CI: Drop netlify related code and "please <stuff>" actions
(PR#3298) Doc: Document default values in the JSDoc
(PR#3316) Funding: Add link to GitHub sponsors in funding
(PR#3301) Test: Poisoning checks compatible with watch mode
(PR#3330) Test: Make sure poisoning spec never forget one global

3.2.0

Stop copying the Error into the thrown one but use cause when asked too [Code][Diff]

Features

(PR#2965) Attach the original Error as a cause of thrown one
(PR#3224) Attach real errors to internal failures

Fixes

(PR#3225) CI: Publish @fast-check/poisoning on CodeSandbox's builds
(PR#3260) Doc: Sync with current path
(PR#3264) Doc: Improve grammar in HowItWorks
(PR#3292) Test: Stabilize tests of SlicedBasedGenerator

3.1.4

Increased resiliency to poisoned globals [Code][Diff]

Fixes

(PR#3172) Bug: Fix some remaining accesses to global properties
(PR#3165) Bug: Resist to poisoning of top-level types
(PR#3184) CI: Require renovate to always try to dedupe
(PR#3186) CI: Adapt configuration for new ts-jest
(PR#3194) CI: Attempt to fix "please deploy"
(PR#3196) CI: Build every package for "please deploy"
(PR#3208) CI: Better PRs for changelogs cross packages
(PR#3156) Doc: Add missing changesets in changelog of 2.21.0
(PR#3185) Refactor: Attach a depth onto globals internally
(PR#3157) Script: Less verbose description for PRs of CHANGELOG
(PR#3174) Test: Add tests dropping all globals
(PR#3183) Test: Add some more type related tests for oneof
(PR#3076) Test: Check arbitraries do not cause any poisoning
(PR#3205) Test: Add missing "typecheck" scripts on packages

3.1.3

More resilient to external poisoning on all arbitraries [Code][Diff]

Fixes

(PR#3094) Bug: Make numeric arbitraries resistant to poisoning
(PR#3096) Bug: Make single char arbitraries resistant to poisoning
(PR#3097) Bug: Make simple combinators arbitraries resistant to poisoning
(PR#3098) Bug: Make array combinators arbitraries resistant to poisoning
(PR#3099) Bug: Make multi chars arbitraries resistant to poisoning
(PR#3102) Bug: Fix safeApply never calling original apply
(PR#3103) Bug: Make object arbitraries resistant to poisoning
(PR#3104) Bug: Make typed arrays arbitraries resistant to poisoning
(PR#3106) Bug: Make recursive arbitraries resistant to poisoning
(PR#3107) Bug: Make function arbitraries resistant to poisoning
(PR#3108) Bug: Make complex strings arbitraries resistant to poisoning
(PR#3143) Bug: Make webFragments/Segment/QueryParameters resistant to poisoning
(PR#3152) Bug: Protect string generators against poisoning
(PR#3101) CI: Do not suggest private packages during version bumps
(PR#3113) CI: Consider ⚡️ aka zap PRs as fixes for changelog
(PR#3111) CI: Try to configure renovate to open more PRs
(PR#3150) CI: Change update strategy for renovate
(PR#3151) CI: Update bump strategy of renovate
(PR#3141) Clean: Drop unused dependencies
(PR#3100) Performance: Drop unneeded copy for full custom uniqueArray
(PR#3105) Performance: Faster implementation for safeApply
(PR#3112) Performance: Speed-up all safe versions built-in methods
(PR#3109) Refactor: Extract and share code computing safe versions for built-ins
(PR#3154) Script: More verbose CHANGELOG script and continue on failure

3.1.2

More resilient to external poisoning on assert and property [Code][Diff]

Fixes

(PR#3082) Bug: Protect assert from poisoned Math or Date
(PR#3086) Bug: Resist to poisoning of Object
(PR#3087) Bug: Resist to poisoning of Function/Array/String
(PR#3089) Bug: Clear poisoning instability in filter, map, chain
(PR#3079) CI: Auto-cancel previous runs on new commits
(PR#3088) Script: Add script to run e2e tests in debug mode
(PR#3092) Script: Better handle new projects in changelog generator
(PR#3081) Test: Add some poisoning e2e for fast-check
(PR#3085) Test: Check poisoning against noop arbitrary (for now)

3.1.1

Better package.json definition and __proto__ related fixes [Code][Diff]

Fixes

(PR#3066) Bug: Export package.json
(PR#3070) Bug: Support __proto__ as key in record
(PR#3068) Test: Fix test comparing stringify and JSON.stringify
(PR#3069) Test: Fix tests on record wrongly manipulating __proto__

3.1.0

Generate more dangerous strings by default [Code][Diff]

Features

(PR#2975) Sanitize constraints used internally by "oneof" as much as possible
(PR#3048) Add experimental "custom slices" constraint on array
(PR#3043) Generate dangerous strings by default

Fixes

(PR#3049) Bug: Fix out-of-range in SlicedBasedGenerator
(PR#3050) Bug: Allow strange keys as keys of dictionary
(PR#3051) Bug: Better rounding in statistics
(PR#3052) CI: Add missing Ubuntu env for e2e
(PR#3047) Refactor: Implement sliced based generator for arrays
(PR#3059) Script: Add links to buggy PRs in changelog PR
(PR#3060) Script: Only commit package.json corresponding to impacted CHANGELOGs

3.0.1

Basic setup for monorepo [Code][Diff]

Fixes

(PR#2986) CI: Switch to Yarn 3 and simple monorepo
(PR#2987) CI: Simplify test-bundle script following merge of Yarn 3
(PR#2988) CI: Switch to yarn workspace * instead of cd packages/*
(PR#2990) CI: Replace npx by yarn dlx
(PR#2991) CI: Setup prettier at the root of the project
(PR#2992) CI: Drop unneeded benchmarks
(PR#2993) CI: Fix script not using the right path
(PR#2994) CI: Fix gh-pages publication follwoing move to monorepo
(PR#2995) CI: Clean-up .gitignore
(PR#2996) CI: Move eslint at top level
(PR#2989) CI: Make fast-check self reference itself as a dev dependency
(PR#2997) CI: Define top-level script to simplify build and test
(PR#2999) CI: Setup for yarn version check
(PR#3001) CI: Make use of yarn version for generate changelog
(PR#3003) CI: Fix usages of yarn version when generating changelog
(PR#3005) CI: Move anything package related next to its package
(PR#3008) CI: Check the need for dedupe for each run
(PR#3010) CI: Cross-jobs caching for yarn
(PR#3011) CI: Enhance and document version related rules for PRs
(PR#3014) CI: Run tests against trimmed versions of the packages
(PR#3015) CI: Make fast-check's tests rely on its own build
(PR#3017) CI: Faster workflow of GH Actions
(PR#3023) CI: Factorize test jobs via matrix of GH Actions
(PR#3024) CI: Drop es-check related jobs
(PR#3032) CI: Handle monorepo in generate changelog
(PR#3034) CI: Better links in PR generating changelog
(PR#3037) CI: Adapt build script to publish any package
(PR#3039) CI: Also commit .yarn/versions with changelogs
(PR#3000) Doc: Default to readme from packages/fast-check
(PR#3006) Doc: Start following all-contributors specification
(PR#3007) Doc: Rework the "bug discovered with fast-check" section of the README
(PR#3031) Doc: Add missing README files on bundle related tests
(PR#2982) Move: Move example/ to examples/
(PR#2983) Move: Move part of test/ into packages/test-bundle-*
(PR#2984) Move: Move part of source code into packages/fast-check
(PR#2977) Refactor: Simplify logic to read constraints for commands
(PR#3016) Test: Check SHA1 of produced bundle in E2E tests

3.0.0

Easier and more expressive thanks to the full support of size and a new and extensible API for custom arbitraries [Code][Diff]

This new major of fast-check is:

extensible: extending the framework with custom arbitraries made easy
expressive properties: write properties corresponding to specs without dealing with internals of the library (more)
recursive structures: better native handling of recursive structures without any tweaks around internals
unified signatures: unify signatures cross-arbitraries (more)

Breaking changes

(PR#2927) Remove deprecated signatures of fc.array
(PR#2929) Remove deprecated signatures of fc.string
(PR#2930) Remove deprecated signatures of fc.*subarray
(PR#2931) Remove deprecated signatures of fc.commands
(PR#2932) Remove deprecated signatures of fc.option
(PR#2933) Remove deprecated signatures of fc.json
(PR#2934) Remove deprecated signatures of fc.lorem
(PR#2935) Drop support for TypeScript 3.2 (min ≥4.1)
(PR#2928) Rely on new implementations and APIs for fc.float/fc.double
(PR#2938) Remove fully deprecated arbitraries
(PR#2939) Remove deprecated signatures of fc.integer
(PR#2940) Get rid off genericTuple (replaced by tuple)
(PR#2941) Remove forked typings for pure-rand
(PR#2942) Change the API of a property to rely on the modern one
(PR#2944) Switch to the new API of Arbitrary and remove old variants
(PR#2945) Rename NextValue into Value
(PR#2949) No depthFactor specified means: use defaulted configuration
(PR#2951) Stop defaulting maxKeys and maxDepth on object arbitraries
(PR#2952) Stop defaulting maxCount on lorem
(PR#2954) Stop defaulting defaultSizeToMaxWhenMaxSpecified to true
(PR#2959) Change the output of Property::run to return the original error
(PR#2960) Remove frequency now replaced by oneof
(PR#2970) Rename depthFactor into depthSize and invert numeric

You may refer to our migration guide in case of issue: https://github.com/dubzzz/fast-check/blob/main/MIGRATION2.X_TO_3.X.md_

Features

(PR#2937) Adopt variadic tuples for signatures of clone
(PR#2936) Adopt variadic tuples for signatures of property
(PR#2950) Add the ability to define use max as depth factor
(PR#2953) Extend usage of defaultSizeToMaxWhenMaxSpecified to depth
(PR#2955) Add support for weighted arbitraries in oneof
(PR#2962) Forward the original Error into RunDetails
(PR#2956) Add big int typed arrays arbitraries
(PR#2968) Better typings for letrec

Fixes

(PR#2963) Bug: Allow property to intercept thrown symbols
(PR#2925) CI: Add type-checking only step and script
(PR#2923) CI: Format all the files not only TS ones
(PR#2964) CI: Check the generated lib against ES standard
(PR#2918) Doc: Update "Question" template to request users to prefer "Discussions"
(PR#2920) Doc: Add some statistics for jsonValue in the documentation
(PR#2966) Doc: Fix link to timeout section in tips doc
(PR#2919) Refactor: Replace usages of set by uniqueArray
(PR#2921) Refactor: Replace deprecated usages of integer by constraint-based ones
(PR#2924) Refactor: Move ts-jest types related helpers internally
(PR#2946) Refactor: Clean src thanks to NextArbitrary
(PR#2948) Refactor: Adapting some code in anything thanks to TODO
(PR#2971) Script: Support breaking changes in generated CHANGELOG
(PR#2973) Script: Support typing related PRs in CHANGELOG
(PR#2943) Test: Rewrite tests on commands based on NextArbitrary
(PR#2947) Test: Remove "Next" from test helpers
(PR#2961) Test: Ensure fc.sample can run against properties and arbitraries