React/Jest Mocking issue with keymirror

[blainekasten]

I've ran into an issue with 0.14 when testing with jest & npm 3. Ultimately I've realized that since npm 3 installs everything as siblings, packages that react depends on will still get automatically mocked and therefore break.

My example was an error like this:

● Runtime Error
TypeError: /Users/blaine.kasten/Sites/videochrome/src/ProgressBar/ProgressBarBackground/__tests__/ProgressBarBackground--tests.js: /Users/blaine.kasten/Sites/videochrome/node_modules/react/react.js: /Users/blaine.kasten/Sites/videochrome/node_modules/react/lib/React.js: /Users/blaine.kasten/Sites/videochrome/node_modules/react/lib/ReactDOM.js: /Users/blaine.kasten/Sites/videochrome/node_modules/react/lib/ReactDefaultInjection.js: /Users/blaine.kasten/Sites/videochrome/node_modules/react/lib/BeforeInputEventPlugin.js: Cannot read property 'topCompositionEnd' of undefined

Looking into it, in the lib/BeforeInputEventPlugin.js file, it referenced ./EventConstants, in that file it was using fbjs/lib/keymirror to create it's EventConstants. Since that was being mocked, the return from ./EventConstants.js was undefined. Thus causing an error.

This might be part of a bigger problem with jest and supporting npm3. I'm not sure if this issue should live in their repo. Or more immediately react could not depend on fbjs and just use it's own keymirror implementation.

[zpao]

Yea, this automocking stuff is now more annoying… yayyyy. I tend to have more issues with automocking than gains from not using it, so my first move is pretty much always to just disable it for everything. This isn't going to be React specific - anybody who had disabled mocking for a dependency with dependencies will have problems - but will definitely be part of the story of testing React. It's probably worth bringing up in the jest repo so it's on people's radar. I'll bug @cpojer about it too :P

Or more immediately react could not depend on fbjs and just use it's own keymirror implementation.

keyMirror is only 1 of the things that got moved to fbjs. We'd have to move a bunch of things back into the react repo and that's really unlikely.

[cpojer]

Can we just kill keyMirror? We don't need it at all.

[zpao]

That can be a separate discussion. keyMirror is a symptom here but the root of this issue is jest + npm.

[blainekasten]

This is getting really bad. I ran into this again (sort of my own fault). I set my unmock to "fbjs/lib/keymirror" which I should have just done "fbjs".

This just popped up again with a deep issue:

In react/lib/Danger you required fbjs/lib/createNodesFromMarkup which is called on L89 then looped over. Unfortunately the mock made that function return undefined, which errored on the .length in L92.

So, @cpojer like @zpao said, there are symptoms here. But this is seeming to be a deep jest issue. Should I migrate this issue to the jest repo? do you have one already?

[cpojer]

I agree this situation is really annoying. I don't have a good solution for this yet and I would recommend for the React team to provide a list of modules that should not be mocked until we come up with something good. Sorry for the trouble.

[zpao]

Yea, we should make this a jest issue but with a React specific work-around - unmock react and fbjs, and hopefully don't use any dependencies of fbjs. Basically anytime you unmock something you need to walk down it's deps and unmock all of those or you're in potential trouble.

[justinwyllie]

Is there any kind of a resolution for this?
I am using: npm 3.3.6 and Jest 0.7.1
I am trying to not mock react-bootstrap. My test fails with either 'TypeError' or 'SyntaxError'. I added some of the modules suggested in the comments above to unmockedModulePathPatterns in my package.json. i also followed through all the dependencies of react-bootstrap and unmocked them in my test. I had to upgrade node to support Jest and that installed npm 3.3.6.

[zpao]

@justinwyllie Personally I suggest either unmocking everything or downgrading to npm2. Unfortunately we don't have the time to play whack-a-mole.

[cpojer]

This will be fixed in jest 0.8.0 or 0.8.1 towards the end of the year. I have a clear solution in mind but I need to make sure it will work out fine.

[cpojer]

I recommend adding all of the modules from here: https://github.com/react-bootstrap/react-bootstrap/blob/master/package.json#L114 to your unmock patterns.

[blainekasten]

Is this supposed to be fixed in jest-cli@0.9.0? @cpojer

[cpojer]

Not yet! I have a fix that I need to add tests for and tests for performance. It will definitely be fixed with the final 0.9 though :)

[cpojer]

I'll publish a new version of jest-cli@next (0.9 pre-release) that fixes this issue today.

[blainekasten]

MAY THE GODS BE PRAISED

On Sun, Feb 21, 2016 at 6:18 PM, Christoph Pojer notifications@github.com
wrote:

I'll publish a new version of jest-cli@next (0.9 pre-release) that fixes
this issue today.

—
Reply to this email directly or view it on GitHub
#5183 (comment).

[cpojer]

Jest 0.9.0 was published along with a complete overhaul of the website: facebook.github.io/jest/ This problem should not be an issue again :)