Vue Test Utils Peer dependency issue reproducers

Yarn

When using yarn pnp or the pnpm linker for yarn, @vue/test-utils is unable to access @vue/compiler-dom because the peer dependency is not declared. Yarn treats this as unsound and ambiguous and fails, where as npm would silently allow this to work as long as something somewhere installed some version of that package.

To reproduce:

cd yarn
yarn install
yarn run test

PNPM

When using pnpm, a similar behavior to npm is performed where dependencies will be hoisted to ./node_modules/.pnpm/node_modules/** using symlinks. This is a compatibility shim to handle cases where undeclared dependencies are referenced. This solves the problem that the Yarn pnp / pnpm linkers had in that we are now able to find @vue/compiler-dom, however, it introduces another problem in that the version of @vue/compiler-dom being used isn't guaranteed to match the version of vue the package depends on when you are in a monorepo.

The pnpm reproducer makes use of a monorepo with two sub-packages that both reference different versions of vue. The tests expect that the version of @vue/compiler-dom used matches the version of vue and this will fail for one of the two packages. This may be the source of subtle bugs since there is now a mismatch between the vue version and the @vue/compiler-dom package.

cd pnpm
pnpm install
pnpm run test

NPM

When using npm, the hoisting behavior is different from pnpm when there is a conflict in the vue versions. With npm, one set of vue packages will be hoisted to the root, and the other set will be nested in packages/b/node_modules. In this case, the reproducer is providing a different set of errors and the test is failing trying to mount the component in vue internals for one of the two packages.

cd npm
npm install
npm run test