fix(order): find modules from each chunk in group

[ryansully]

fixes #257

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

As discussed in #257, when the plugin calls modulesByChunkGroup, it calls the chunk group's getModuleIndex2() function from the ChunkGroup object's _moduleIndices2 Map property. However, the error occurs because the module it's trying to find the index for doesn't exist in _moduleIndices2, causing modulesByChunkGroup to return an empty array. The for loop that uses the array never iterates, so bestMatch is never set and is left undefined, resulting in an error when trying to call .pop() on that undefined object.

This fix checks if getModuleIndex2() returns no matching modules and, if so, dives into each chunk in the chunk group to find matching modules.

Breaking Changes

None.

Additional Info

While this solution dives into a chunk group's chunks to find modules that weren't in the chunk group's _moduleIndices2 property, it might indicate a bug in webpack where that property is not being fully populated as it should be. If that is the case, then this fix should no longer be necessary, but perhaps it wouldn't hurt to have an extra guard for finding chunk modules.

[jsf-clabot]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #455 (312ad6d) into master (50434b5) will decrease coverage by 0.82%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master     #455      +/-   ##
==========================================
- Coverage   88.17%   87.34%   -0.83%     
==========================================
  Files           5        5              
  Lines         406      411       +5     
  Branches       86       87       +1     
==========================================
+ Hits          358      359       +1     
- Misses         46       50       +4     
  Partials        2        2              

Impacted Files	Coverage Δ
src/index.js	85.57% <33.33%> (-1.68%)	⬇️

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[alexander-akait]

Can we add tests?

[ryansully]

I will add tests soon so the coverage delta doesn't change.

[ryansully]

I'm afraid writing a test for this will be difficult; running tests locally fails for me and I haven't been able to get them to pass.

(The lint:prettier script also fails with an error, so I disabled it just to get Jest to run.)

[alexander-akait]

Just use prettier to fix problem

[doried-a-a]

Thanks folks for being working on this. Any updates?