lerna-yarn-test

Testing file: and link: specifiers with yarn and lerna. There are subtle differences, noted in the Findings section.

Getting started

Requirements:

• Docker Daemon running in background
• Node v14

nvm use
yarn install
# This example uses a private registry
yarn start:registry

This will start a registry at http://0.0.0.0:4873. Via UI, login as admin:admin.

Findings

• ✅ Lerna will respect both file: and link: specifiers for publishing. An actual version will be substituted.
  • Tested file: with @myexample/b@<=0.0.3
  • Tested link: with @myexample/b@>=0.0.4
• ✅ Yarn will make a symlink for dependencies using the link: specifier.
• ❌ Yarn will make a complete copied subtree of a dependency using the file: specifier (instead of a symlink). This seems like a bug. In large monorepo setups, this is a very expensive operation as well.

tl,dr

Use link: specifiers. They don't appear to be part of the official NPM package.json spec, though it's fine for a yarn-based workflow.

Reading

• https://medium.com/@alex_young/npm-5-and-file-urls-3c3631f7367c
• npm/npm#15900