Fix TypeError: Cannot read property 'className' of undefined

[yamafaktory]

We are using jest-glamor-react in production in our company and so far, this is a super piece of code. Thanks for your awesome work 👍!

What:

I've recently (first time ever) faced a weird issue in some of our (non open-sourced) components:

TypeError: Cannot read property 'className' of undefined

      221 |     inputAA.simulate('change')
      222 |     wrapper.update()
    > 223 |     expect(wrapper).toMatchSnapshot()
          |                     ^
      224 |     expect(wrapper.find('input#a-property-a').prop('checked')).toBeTruthy()
      225 |     // Check the mock function calls after saving.
      226 |     wrapper

      at getSelectorsFromProps (node_modules/jest-glamor-react/dist/utils.js:44:25)
      at node_modules/jest-glamor-react/dist/utils.js:35:14
          at Array.reduce (<anonymous>)
      at getSelectors (node_modules/jest-glamor-react/dist/utils.js:31:16)
      at Function.print (node_modules/jest-glamor-react/dist/serializer.js:38:23)
      at printPlugin (node_modules/pretty-format/build/index.js:287:16)
      at printer (node_modules/pretty-format/build/index.js:332:12)
      at plugin.serialize.plugin.print.valChild (node_modules/pretty-format/build/index.js:289:23)
      at Object.print (node_modules/enzyme-to-json/createSerializer.js:22:14)
      at printPlugin (node_modules/pretty-format/build/index.js:287:16)
      at prettyFormat (node_modules/pretty-format/build/index.js:485:16)
      at Object.throwingMatcher (node_modules/expect/build/index.js:316:33)
      at Object.<anonymous> (src/components/Channels/ChannelSelector.test.jsx:223:21)

The error is thrown only because of the snapshot creation. Removing the expect(wrapper).toMatchSnapshot() line fixes it (but this obviously not what we want).

We are using Enzyme and all the other tests are passing (i.e. nothing is broken). The issue was triggered after splitting one component in smaller chunks.

Why:

For some reason, the props are undefined in the getSelectorsFromProps method (utils). Consequently, an error is thrown in https://github.com/kentcdodds/jest-glamor-react/blob/master/src/utils.js#L37-L38 when trying to access the className property of the props object.

How:

The changes involved are quite simple, returning an empty array early actually solves it. The unit tests of the repository are passing and our tests are not altered at all (a good sign!).

[yamafaktory]

Sorry for the noise, but it was missing in the .gitignore file 😄.

[kentcdodds]

Sounds good 👍

[kentcdodds]

Looks like we need a test for this. Could you add one?

[codecov]

Codecov Report

Merging #38 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #38   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           4      4           
  Lines         158    159    +1     
  Branches       41     42    +1     
=====================================
+ Hits          158    159    +1

Impacted Files	Coverage Δ
src/utils.js	100% <100%> (ø)	⬆️

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[yamafaktory]

@kentcdodds Thanks a lot for the quick feedback 🚀🎉. I've added a small test case for that weird corner case.

[kentcdodds]

Super-duper. Thanks!

[yamafaktory]

@kentcdodds Thanks a ton ❤️!