[Proposal] Use Jest with Mocha Runner by rogeliog · Pull Request #6442 · babel/babel

rogeliog · 2017-10-07T22:58:59Z

Q	A
Fixed Issues?
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	👍
Documentation PR
Any Dependency Changes?	👍

This is just a proposal, and I completely understand if you don't want to move forward with this, or if it does not align with the direction of the project.

Jest 21 comes with support for custom runners, jest-runner-mocha enables a Mocha code base to run on Jest.

Allows the codebase to start using Jest as a test runner, while still use Mocha as a test framework
Once Jest is being used as a test runner, we could add multiple --projects and slowly migrate the tests to use Jest as a test framework jest --projects jest-mocha.config.js jest.config.js
Requires minimal code changes
I've seen this WIP: Migrate to jest #6179, which I hope that this proposal would help as a stepping stone for it.
It reduces the total test run time 😄

Pending Items

Use Jest in the package.json scripts
Remove unused files as a result of this change
Remove any unused dependencies as a result of this change
Enable jest --coverage... This should not be that much trouble, it already works with other codebases, but I think it there are some caveats with to make it work with Babel 7
Reenable skipped tests... I was having some trouble with two tests in packages/babel-register/test/index.js

Thanks for everything!

Andarist · 2017-10-07T23:08:23Z

Im new to the project, cant speak for others. From my perspective it would be really great to migrate to jest and eventually leverage its snapshots feature with the interactive mode.

babel-bot · 2017-10-07T23:09:40Z

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/6961/

Andarist · 2017-10-07T23:10:34Z

package.json

      "eslint --format=codeframe --rulesdir='./scripts/eslint_rules'"
    ]
+  },
+  "jest": {


wouldn't we need to alias packages/* to their respective src directories to have a great watch mode?

I think I'm missing something, because I'm not sure that I understood that

Sorry if I was not clear. The source code in packages gets transpiled in a build step, to have great save+watch tests experience I think it would be better to integrate transpiling into jest, rather than run separate build with watch mode.

Because packages are linked and treated as regular npm dependencies, the regular node's dependency algorithm kicks in and jest will search for the built files rather than source ones.

hzoo · 2017-10-08T01:16:13Z

This is just a proposal, and I completely understand if you don't want to move forward with this, or if it does not align with the direction of the project.

@rogeliog thanks for the PR (and appreciate you opening it as a proposal)! This is really cool, and since it's small easier to review 👌

I've seen this #6179, which I hope that this proposal would help as a stepping stone for it.

Yeah that got blocked/delayed a few times 😄 so this could definetely be a great way to switch over. Babel basically has it's own version of a lot of the tooling and even though it's not really an issue most of the time it would be nice to remove a lot of the code we have to handle testing (own our fixture setup -> snapshots assuming they work well enough).

It reduces the total test run time

The last time we tried this it seemed really slow and we weren't sure why, if that's not the case anymore then great. (make test-only current is 50s-1min on my machine)

If we could remove https://github.com/babel/babel/blob/master/scripts/test.sh, https://github.com/babel/babel/blob/master/scripts/_get-test-directories.sh,
https://github.com/babel/babel/tree/master/packages/babel-helper-plugin-test-runner
https://github.com/babel/babel/tree/master/packages/babel-helper-transform-fixture-test-runner

Assuming jest + maybe something like https://github.com/babel-utils/babel-plugin-tester can cover those, would like to use a better watch mode than what we say in https://github.com/babel/babel/blob/master/CONTRIBUTING.md#running-lintingtests. And we don't have the easier setup in updated fixtures without just rm the files

rogeliog · 2017-10-08T21:26:52Z

Time comparison on my machine:

Before:

After:

NOTE: Running with Jest is resulting in 68 tests that it is still not picking up, I'll need to investigate that.

Yes I think we could remove https://github.com/babel/babel/blob/master/scripts/test.sh and https://github.com/babel/babel/blob/master/scripts/_get-test-directories.sh...

For https://github.com/babel/babel/tree/master/packages/babel-helper-plugin-test-runner and
https://github.com/babel/babel/tree/master/packages/babel-helper-transform-fixture-test-runner I think that would need to happen until tests are being run by Jest.

Which by the way you could run full Jest tests and (Mocha + Jest) tests at the same time jest --projects and slowly migrate all of them or whatever it the best path for it.

I think that the watcher would still need to be run cross package linking.

existentialism · 2017-10-09T14:29:43Z

package.json

+  "jest": {
+    "runner": "jest-runner-mocha",
+    "testMatch": [
+      "<rootDir>/packages/**/test/*.js"


Should include codemods/. (experimental/ as well, though babel-preset-env will need a bit of work to work with jest, I imagine... can do that in a followup PR).

Just FYI, now, the experimental doesn't exists anymore. Only codemods must be included here.

danez · 2017-10-13T22:22:53Z

packages/babel-register/test/index.js

 const DATA_ES2015 = require.resolve("./__data__/es2015");

-describe("babel-register", function() {
+xdescribe("babel-register", function() {


So the babel-register test also don't work with jest-mocha-runner? That was the biggest blocker for the other PR because there is no way in jest to test require hooks.

So we would either need to make a special case for these tests and not run them with jest or stay with mocha/ava.

I'm fine with doing a special case for this if we want to use jest

xtuc · 2018-02-23T19:12:58Z

Could you please include the codemods folder in the tests?

hzoo · 2018-02-23T19:17:27Z

I think we can just rebase and land this ourselves if we are good

rogeliog · 2018-02-25T00:22:48Z

@hzoo Perfect! I'm working on rebasing it today, and but there are some issues with one test. I'll try to have something up by today/tomorrow

hzoo · 2018-02-25T00:25:50Z

Sorry for the delays again! Even suggested if someone had time we could instead of you 😁. Thanks again

rogeliog · 2018-02-25T00:31:26Z

I'm more than happy to get this to a point where is mergable! I just pushed after rebasing, I need to step away from my computer today, but I'll keep working on it tomorrow

rogeliog · 2018-02-28T16:45:16Z

Closing in favor of #7455

Use Jest with jest-runner-mocha

774365f

rogeliog force-pushed the jest-runner-mocha branch from e45e795 to 774365f Compare October 7, 2017 23:02

Andarist reviewed Oct 7, 2017

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Remove test/*

0d24856

xtuc added area: tests PR: Internal 🏠 A type of pull request used for our changelog categories labels Oct 9, 2017

existentialism reviewed Oct 9, 2017

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danez reviewed Oct 13, 2017

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SimenB mentioned this pull request Oct 14, 2017

WIP: Migrate to jest #6179

Closed

hzoo added the Priority: High label Oct 17, 2017

jridgewell approved these changes Oct 19, 2017

View reviewed changes

existentialism removed the Priority: High label Jan 11, 2018

existentialism added this to the Babel 7.next milestone Jan 11, 2018

Merge branch 'master' into jest-runner-mocha

b180eb5

Some updates after merging with latest master

9394103

Skip failing test

8d2a2b9

danez mentioned this pull request Feb 28, 2018

Use jest #7455

Merged

rogeliog closed this Feb 28, 2018

lock bot added the outdated A closed issue/PR that is archived due to age. Recommended to make a new issue label Oct 5, 2019

lock bot locked as resolved and limited conversation to collaborators Oct 5, 2019

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