• See https://jestjs.io/blog/2016/09/01/jest-15.html
• Jest by default now also recognizes files ending in .spec.js and .test.js as test files.
• Completely replaced most Jasmine matchers with new Jest matchers.
• Rewrote Jest's CLI output for test failures and summaries.
• Added --env option to override the default test environment.
• Disabled automocking, fake timers and resetting the module registry by default.
• Added --watchAll, made --watch interactive and added the ability to update snapshots and select test patterns in watch mode.
• Jest uses verbose mode when running a single test file.
• Console messages are now buffered and printed along with the test results.
• Fix testEnvironment resolution to prefer jest-environment-{name} instead of {name} only. This prevents a module colision when using jsdom as test environment.
• moduleNameMapper now uses a resolution algorithm.
• Improved performance for small test runs.
• Improved API documentation.
• Jest now works properly with directories that have special characters in them.
• Improvements to Jest's own test infra by merging integration and unit tests. Code coverage is now collected for Jest.
• Added global.global to the node environment.
• Fixed babel-jest-plugin-hoist issues with functions called mock.
• Improved jest-react-native preset with mocks for ListView, TextInput, ActivityIndicator and ScrollView.
• Added collectCoverageFrom to collect code coverage from untested files.
• Rewritten code coverage support.