Use jest-matchers for assertions instead of expect

[skovhus]

Currently expect@1.x is being integrated into Jest (see more background in jestjs/jest#1679).

In jest-codemods I'm working on a codemod to automate the process of going from mjackson/expect to jest-matchers (if running in a browser) or plain Jest (if running in node). 🤖

I've tested the codemod on this project and everything should still work.

Let me know what you think.

Update

Updated 4th Septhember with Expect@21

[mjackson]

Hey @skovhus, thanks for taking a look at this. Do you have any updates here? I'd like to make this upgrade happen sometime soon. Thanks! :)

[skovhus]

@mjackson would you like to still use a browser for executing these tests? If so then I can wrap this PR up using jest-codemods, so you can use the jest-matchers. At one point the jest-matchers package will be renamed to expect, but that should be a small change at that point. : )

[skovhus]

@mjackson I've just reran the codemod on latest master.

If you want to keep running the tests in a browser, there are still some issues with the es5 bundle of jest-matchers. Seems to be something related to IE10.

Let me know which testing environment you would like, node or browser. : )

19 07 2017 13:42:43.316:INFO [IE 10.0.0 (Windows 8 0.0.0)]: Connected on socket -C3IcIu9DHLMDYfIAAAE with id 90097551
IE 10.0.0 (Windows 8 0.0.0) ERROR
  Object expected
  at webpack:///~/jest-matchers/build-es5/index.js:4994:0 <- tests.webpack.js:5330
IE 10.0.0 (Windows 8 0.0.0): Executed 0 of 0 ERROR (0.417 secs / 0 secs)

[mjackson]

Thanks, @skovhus. I need to keep using the browser for these tests because part of this library's job is to work around bugs and/or slightly differing behavior in various browser implementations, so the in-browser tests are crucial. I'd also like to make sure the ES5 build of the next version of expect works well in browsers. The current version of the package works well in browsers, and we need to preserve that if we want to provide a smooth upgrade path.

[skovhus]

@mjackson I totally agree with the browser support for next version of expect/jest-matchers. 👍🏻 So while working on the codemod, I've also been contributing browser support to Jest:

• jest-matchers contains untranspiled code jestjs/jest#3360
• Better browser support jestjs/jest#3421
• Add babel-transform-runtime to browser builds jestjs/jest#3476
• Use rollup for browser builds jestjs/jest#3532

We are just missing a few things it seems. : )

[skovhus]

I'll update this once jestjs/jest#4367 has landed.

[skovhus]

@mjackson master has been merged in now that expect@21 has been released. Should be ready for you to merge. : )

[mjackson]

Thanks @skovhus! I'm taking a look at this now.