test: migrate yarn modern examples to corepack

[MikeMcC399]

• closes Migrate Yarn Modern examples to Corepack #1349

Situation

The two examples for Yarn Modern v4 are currently set up so that the Yarn package manager executables are committed to the repo in each corresponding examples directory under .yarn/releases with the Yarn config parameter yarnPath pointing to the file, for example yarnPath: .yarn/releases/yarn-4.6.0.cjs.

The examples are:

• examples/yarn-modern
• examples/yarn-modern-pnp

The current Yarn Modern Installation instructions recommend managing Yarn through Corepack.

Change

Examples

In each of the examples:

• examples/yarn-modern
• examples/yarn-modern-pnp

1. Remove yarnPath from .yarnrc.yml / remove the file if is it otherwise empty.
2. Remove the directory .yarn
3. Add a hash to packageManager in package.json by executing corepack up
4. Update the README.md file

In the GitHub Actions workflow scripts:

• .github/workflows/example-yarn-modern.yml
• .github/workflows/example-yarn-modern-pnp.yml

add

corepack enable yarn

MAINTENANCE

In docs/MAINTENANCE.md update the requirements to incorporate corepack.

• Remove the script scripts/check-package-manager-yarn.sh
• Update the script scripts/update-cypress-latest-yarn.sh to install Yarn 1 Classic and use corepack for Yarn Modern

Verification

Ubuntu 24.04.1 LTS, Node.js 22.13.1 LTS, Corepack 0.30.0 (bundled)

Corepack enabled

corepack enable yarn
cd examples/yarn-modern
yarn
yarn test

cd ../yarn-modern-pnp
yarn
yarn test

• Dependencies should be installed and tests run without errors, apart from known issue "Most NODE_OPTIONs are not supported in packaged apps" when using yarn pnp cypress#19229 when running Yarn Plug'n'Play test.

Corepack disabled

corepack disable yarn
npm install yarn@latest -g
cd examples/yarn-classic
yarn
yarn test

Dependencies should be installed and tests run without errors.

Cypress update

corepack disable yarn
corepack disable pnpm
npm install pnpm@latest -g
git clean -xfd
npm run update:cypress

Cypress should be updated without error in all examples.

All package managers should still be available:

npm -v # 10.9.x
yarn -v # 1.22.x
pnpm -v # 9.15.x

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.