unable to require('when') (cujojs/when) in test

[honzatrtik]

Hello!
My test file is as simple as

var when = require('when');

but still throws error even if i disable mocking using jest.dontMock('when')

/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/when/when.js: Cannot read property 'resolve' of undefined
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/when/when.js:35:28
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/when/when.js:229:96
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/when/when.js:11:1
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/when/when.js:229:3
    at Object.runContentWithLocalBindings (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/lib/utils.js:357:17)
    at Loader._execModule (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:245:9)
    at Loader.requireModule (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:900:12)
    at Loader.requireModuleOrMock (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:921:17)
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/src/components/gig-list/__tests__/filter-genre-group.js:13:12
    at Object.runContentWithLocalBindings (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/lib/utils.js:357:17)
    at Loader._execModule (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:245:9)
    at Loader.requireModule (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:900:12)
    at jasmineTestRunner (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/jasmineTestRunner/jasmineTestRunner.js:239:16)
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/TestRunner.js:371:12
    at _fulfilled (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/node_modules/q/q.js:798:54)
    at self.promiseDispatch.done (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/node_modules/q/q.js:827:30)
    at Promise.promise.promiseDispatch (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/node_modules/q/q.js:760:13)
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/node_modules/q/q.js:574:44
    at flush (/Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/node_modules/q/q.js:108:17)
    at /Users/honzatrtik/Workspace/bandzone3/src/www/js2/node_modules/jest-cli/src/lib/FakeTimers.js:259:7
    at process._tickCallback (node.js:419:13)

Is there any workaround?

[wwalser]

https://github.com/cujojs/when/blob/master/when.js#L22

I'm pretty sure jest.dontMock('when') will still mock everything between lines 13 and 22. In this case I think the solution is to use config.unmockedModulePathPatterns. See: https://facebook.github.io/jest/docs/api.html#config-unmockedmodulepathpatterns-array-string

[benzen]

I get into the same trap, thanks to @wwalser it's was easy to get out.
Still, it seems to me that even if the module that my moduleUnderTest depends are mocked out.
The module they depend on are still required (i mean node's required) and then mocked out.

Maybe it will be clearer as a draw:
A -> B -> C

The module i'm testing is A. When testing it, i'm expecting B to be mocked and not to require C for real.
But it seams to me that what is happening is this:

A -> mock(B) -> B -> mock(C) -> C

Is this because of the automatic construction of the mock ?

Also, it seems to me that the doc pointed by @wwalser has some syntaxe issue, almost always and almost all the time

[wwalser]

It sounds like you've already caught on to what is happening, your illustration is close to accurate. Actually the real requires of b and c happen before the mock can be constructed.

They are required into a sandboxed context and inspected in order to create a mocked version. It's expected behavior.

In every case that I've seen this is only a problem when simply requiring a module causes side effects which I tend to treat as an antipattern in my own code.

[browniefed]

I've added when to the unmockedModulePatterns as well as other variations of regular expressions to attempt to not mock out lines 13-22 however nothing seems to be working. Is there a documented unmockedModulePatterns for this somewhere?

[cpojer]

This will be fixed in 0.9.0. You can try it with jest-cli@next already. Otherwise I recommend unmocking it using unmockedModulePathPatterns.

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.