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Sorry for the dumb question, but as a JS (and JS testing) newbie, could someone explain how Jest is different from Jasmine (from which it's built on) or, say, f

• vjeux 12y ago
  Jasmine provides you with the testing primitives such as describe(), it(), expect(value).toEqual(other): http://facebook.github.io/jest/docs/api.html#globally-injected-variables http://facebook.github.io/jest/docs/api.html#globally-inject... Jest adds multiple layers on-top: - A mock library (also called stubs) in order to create fake functions and assert that they are called as you want: http://facebook.github.io/jest/docs/mock-functions.html#content http://facebook.github.io/jest/docs/mock-functions.html#cont... - A way to provide an alternate implementation for dependencies using require(): http://facebook.github.io/jest/docs/common-js-testing.html#content http://facebook.github.io/jest/docs/common-js-testing.html#c... - It inspects the shape of your dependencies and return a mocked version of them: http://facebook.github.io/jest/docs/automatic-mocking.html#content http://facebook.github.io/jest/docs/automatic-mocking.html#c... - Finally, it works in node instead of the browser and uses jsdom to let you test code related to the DOM. (It also runs tests in parallel)
  • jeffmo 12y ago
    jinx!
  • nlh 12y ago
    Many thanks! (to both of you ;)
  • kumar303 12y ago
    Can someone copy/paste this into the docs? :) It was really helpful, thanks.
    • jeffmo 12y ago
      I went ahead and added it to the main page of the website: http://facebook.github.io/jest/ http://facebook.github.io/jest/
• jeffmo 12y ago
  jasmine and mocha are test frameworks (they're the things that supply your describe() and it() functions), but they don't really supply you with everything you need to get set up to run tests. jest is a test runner that includes a few additional things to try to make all aspects of writing and running tests a little easier...such as: * Searches for tests to find + execute so that you can put tests near the modules they are testing * Runs tests in parallel processes so that your test runs finish sooner * Replace's node's built-in require() function with a custom one that acts almost entirely the same -- except (by default) it returns mocked versions of modules (rather than the real things) when your tests run * Gives you a fake DOM implementation (using jsdom) so that you can test code that depends on DOM APIs on the command line without having to boot up a browser
  • nlh 12y ago
    Fantastic. Great answer and now much clearer to me. Thanks! (both of you ;)
  • tieTYT 12y ago
    Nice. When will there be a grunt plugin for it? I'm using the qunit plugin right now and I notice that it's 10x slower to run than viewing it in the browser. This 10 second feedback loop is driving me crazy.
    • andwaal 12y ago
      Rule number one of Grunt: "If you can npm it, you soon will be able to Grunt it(or Gulp it for that matter)"
    • jeffmo 12y ago
      About a month or three ago I hacked up a grunt task for React, but it wasn't very useful since we hadn't opensourced Jest yet. The code is now a little stale and dated, but it basically just shells out to the bin/jest.js script included with Jest. Turned out no more than a ~30lines: https://github.com/jeffmo/react/commit/7a72cbba0eb57844f4e22a1971947b31d685b0e8#diff-1 https://github.com/jeffmo/react/commit/7a72cbba0eb57844f4e22...
• jeffmo 12y ago
  BTW, I've updated the main page of the site to give some more context here -- thanks for asking the question!