18.0.0

See https://jestjs.io/blog/2016/12/15/2016-in-jest.html

• The testResultsProcessor function is now required to return the modified results.
• Removed pit and mockImpl. Use it or mockImplementation instead.
• Fixed re-running tests when --bail is used together with --watch.
• pretty-format is now merged into Jest.
• require('v8') now works properly in a test context.
• Jest now clears the entire scrollback in watch mode.
• Added expect.any, expect.anything, expect.objectContaining, expect.arrayContaining, expect.stringMatching.
• Properly resolve snapshotSerializers, setupFiles, transform, testRunner and testResultsProcessor instead of using path.resolve.
• --testResultsProcessor is now exposed through the cli.
• Renamed --jsonOutputFile to --outputFile.
• Added jest-editor-support for vscode and Nuclide integration.
• Fixed test.concurrent unhandled promise rejections.
• The Jest website is now auto-deployed when merging into master.
• Updated testRegex to include test.js and spec.js files.
• Fixes for babel-plugin-jest-hoist when using jest.mock with three arguments.
• The JSON global in jest-environment-node now comes from the vm context instead of the parent context.
• Jest does not print stack traces from babel any longer.
• Fake timers are reset when FakeTimers.useTimers() is called.
• Usage of Jest in watch mode can be hidden through JEST_HIDE_USAGE.
• Added expect.assertions(number) which will ensure that a specified amount of assertions is made in one test.
• Added .toMatchSnapshot(?string) feature to give snapshots a name.
• Escape regex in snapshots.
• jest-react-native was deprecated and now forwards react-native.
• Added .toMatchObject matcher.
• Further improve printing of large objects.
• Fixed NaN% Failed in the OS notification when using --notify.
• The first test run without cached timings will now use separate processes instead of running in band.
• Added .toHaveProperty matcher.
• Fixed Map/Set comparisons.
• test.concurrent now works with --testNamePattern.