MAJOR: Add `DuplicatesPlugin`, versions ranges

[ryan-roemer]

Work

Breaking changes

• --action=versions:
  • Reports: The tsv and text reports have now changed to reflect dependencies hierarchies as installed (e.g., scoped@1.2.3 -> flattened-foo@1.1.1 -> @scope/foo@1.1.1) to a semever range meaning something like as depended (e.g., scoped@1.2.3 -> flattened-foo@^1.1.0 -> @scope/foo@^1.1.1). We expect that this change will provide much more useful information as to how and why your dependency graph impacts what is installed on disk in node_modules and ultimately what ends up in your webpack bundle.
  • Metadata: The following meta fields have been renamed to be easier to understand.
    • skewedPackages → packages: Number of packages with skews.
    • skewedVersions → resolved: Number of unique resolved versions.
    • installedPackages → installed: Number of on-disk installs.
    • dependedPackages → depended: Number of dependency paths.

      Features

• Add range information to all dependency items returned internally for dependencies utilities and ultimately all the way to versions data.
  • Add installed aggregate statistic to versions metadata.
  • Add DuplicatesPlugin webpack plugin.

    Fixes

• BUG: Per-asset meta stats were never set (all 0) before in data.
  • BUG: Multiple package roots incorrectly collapse / don't prefix. Fixes #90

    Miscellaneous

• Updated README.md with note that --action=versions is not filtered to only packages that would have files show up in the --action=duplicates report.
  • Update --action=versions logic to explicitly use semver-compare for sort order.

Try it out

Download this branch:

# In one terminal
$ yarn build-test
$ yarn watch

# In another
$ export WEBPACK_VERSION=4; \
  TODO_DUP_CHECKER=true \
  WEBPACK_MODE=development \
  WEBPACK_CWD=../../test/fixtures/duplicates-cjs \
  NODE_PATH="${PWD}/node_modules/webpack${WEBPACK_VERSION}/node_modules:${PWD}/node_modules" \
  node test/fixtures/packages/webpack.js \
  --config ../../test/fixtures/config/webpack.config.js

You can replace duplicates-cjs with any other scenario from our test fixtures directory

[codecov[bot]]

Codecov Report

Merging #88 into master will increase coverage by 0.67%. The diff coverage is 88.38%.

@@            Coverage Diff             @@
##           master      #88      +/-   ##
==========================================
+ Coverage   89.35%   90.03%   +0.67%     
==========================================
  Files          11       14       +3     
  Lines         498      662     +164     
  Branches       78      105      +27     
==========================================
+ Hits          445      596     +151     
- Misses         37       38       +1     
- Partials       16       28      +12

Impacted Files	Coverage Δ
src/lib/actions/duplicates.ts	94.66% <ø> (ø)	:arrow_up:
src/lib/actions.ts	66.66% <ø> (+66.66%)	:arrow_up:
src/lib/actions/versions.ts	95.2% <100%> (+0.27%)	:arrow_up:
src/plugin/duplicates.ts	86.99% <86.99%> (ø)
src/lib/util/dependencies.ts	94.92% <87.5%> (-0.98%)	:arrow_down:
src/lib/util/files.ts	80% <0%> (-6.67%)	:arrow_down:
src/lib/util/strings.ts	100% <0%> (ø)	:arrow_up:
src/lib/index.ts	100% <0%> (ø)
src/lib/interfaces/modules.ts	100% <0%> (ø)
... and 1 more

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