allow multiple assets to map to the same file on disk

[mxmul]

Fixes #54. When using hashed filenames with file-loader, it's possible that two distinct resources in Webpack will map to the same file on disk (e.g. two copies of the same image). Currently, this plugin will only include one of them arbitrarily in the manifest.

I've switched around this.assetNames to map from original filename to hashed filename to allow all of these assets to appear in the manifest.

This change also resulted in some unexpected manifest entries, caused by the emitFile calls in mini-css-extract-plugin. It seems that the plugin always chose the first occurence of a file asset to intentionally skip over these (#39, #40), so I maintained this behavior by explicitly skipping all emitFile calls from mini-css-extract-plugin. This is admittedly a little jank, but it seems to work.

[codecov-commenter]

Codecov Report

Merging #73 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #73   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          197       197           
=========================================
  Hits           197       197           

Impacted Files	Coverage Δ
src/WebpackAssetsManifest.js	100.00% <100.00%> (ø)

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[webdeveric]

@mxmul Thanks for the PR but I've already fixed this in my dev branch. I'll try to release an update soon.

[kedarv]

@webdeveric I'm think I might be seeing some related behavior on Webpack 5 and webpack-assets-manifest@5.0.6. Can you point me to the commit/option that has this fix in v5?

edit: whoops -- confirmed I'm not seeing this. but, still curious :)

[webdeveric]

@kedarv I think I fixed that in d382887. The findMapKeysByValue function is probably what you're looking for.