20.0.0

• New --projects option to run one instance of Jest in multiple projects at the same time. (#3400)
• New multi project runner (#3156)
• New --listTests flag. (#3441)
• New --showConfig flag. (#3296)
• New promise support for all expect matchers through .resolves and .rejects. (#3068)
• New expect.hasAssertions() function similar to expect.assertions(). (#3379)
• New this.equals function exposed to custom matchers. (#3469)
• New valid-expect lint rule in eslint-plugin-jest. (#3067)
• New HtmlElement pretty-format plugin. (#3230)
• New Immutable pretty-format plugins. (#2899)
• New test environment per file setting through @jest-environment in the docblock. (#2859)
• New feature that allows every configuration option to be set from the command line. (#3424)
• New feature to add custom reporters to Jest through reporters in the configuration. (#3349)
• New feature to add expected and actual values to AssertionError. (#3217)
• New feature to map code coverage from transformers. (#2290)
• New feature to run untested code coverage in parallel. (#3407)
• New option to define a custom resolver. (#2998)
• New printing support for text and comment nodes in html pretty-format. (#3355)
• New snapshot testing FAQ (#3425)
• New support for custom platforms on jest-haste-map. (#3162)
• New support for mocking native async methods. (#3209)
• New guide on how to use Jest with any JavaScript framework. (#3243)
• New translation system for the Jest website.
• New collapsing watch mode usage prompt after first run. (#3078)
• Breaking Change: Forked Jasmine 2.5 into Jest's own test runner and rewrote large parts of Jasmine. (#3147)
• Breaking Change: Jest does not write new snapshots by default on CI. (#3456)
• Breaking Change: Moved the typescript parser from jest-editor-support into a separate jest-test-typescript-parser package. (#2973)
• Breaking Change: Replaced auto-loading of babel-polyfill with only regenerator-runtime, fixes a major memory leak. (#2755)
• Fixed babel-jest to look up the babel field in package.json as a fallback.
• Fixed jest-editor-support's parser to not crash on incomplete ASTs. (#3259)
• Fixed jest-resolve to use is-builtin-module instead of resolve.isCore. (#2997)
• Fixed jest-snapshot to normalize line endings in the serialize function. (#3002)
• Fixed behavior of --silent flag. (#3003)
• Fixed bug with watchers on macOS causing test to crash. (#2957)
• Fixed CLI notify option not taking precedence over config option. (#3340)
• Fixed detection of the npm client in SummaryReporter to support Yarn. (#3263)
• Fixed done.fail not passing arguments (#3241)
• Fixed fake timers to restore after resetting mocks. (#2467)
• Fixed handling of babylon's parser options in jest-editor-support. (#3344)
• Fixed Jest to properly cache transform results. (#3334)
• Fixed Jest to use human-readable colors for Jest's own snapshots. (#3119)
• Fixed jest-config to use UID for default cache folder. (#3380), (#3387)
• Fixed jest-runtime to expose inner error when it fails to write to the cache. (#3373)
• Fixed lifecycle hooks to make afterAll hooks operate the same as afterEach. (#3275)
• Fixed pretty-format to run plugins before serializing nested basic values. (#3017)
• Fixed return value of mocks so they can explicitly be set to return undefined. (#3354)
• Fixed runner to run tests associated with snapshots when the snapshot changes. (#3025)
• Fixed snapshot serializer require, restructured pretty-format. (#3399)
• Fixed support for Babel 7 in babel-jest. (#3271)
• Fixed testMatch to find tests in .folders. (#3006)
• Fixed testNamePattern and testPathPattern to work better together. (#3327)
• Fixed to show reject reason when expecting resolve. (#3134)
• Fixed toHaveProperty() to use hasOwnProperty from Object (#3410)
• Fixed watch mode's screen clearing. (#2959) (#3294)
• Improved and consolidated Jest's configuration file resolution. (#3472)
• Improved documentation throughout the Jest website.
• Improved documentation to explicitly mention that snapshots must be reviewed. (#3203)
• Improved documentation to make it clear CRA users don't need to add dependencies. (#3312)
• Improved eslint-plugin-jest's handling of expect. (#3306)
• Improved flow-coverage, eslint rules and test coverage within the Jest repository.
• Improved printing of expect.assertions error. (#3033)
• Improved Windows test coverage of Jest.
• Refactored configs & transform (#3376)
• Refactored reporters to pass individual Tests to reporters. (#3289)
• Refactored TestRunner (#3166)
• Refactored watch mode prompts. (#3290)
• Deleted jest-file-exists. (#3105)
• Removed Config type. (#3366)
• Removed all usage of jest-file-exists. (#3101)
• Adopted prettier on the Jest codebase.