Build and test only packages that were changed by a PR

[jmuzina]

Since the merging of #57 , we now only version and publish packages that have been updated since the last release action.

We could reduce the time taken to run our CI by further analyzing the changed packages, and only building & testing packages that are changed by a pull request. This can be done using the --since filter.

Here's how this might look:

      - name: Install dependencies
        run: bun run lerna bootstrap --ci --since ${{ github.event.pull_request.base.ref }}

      - name: Build changed packages
        run: bun run lerna run build --since ${{ github.event.pull_request.base.ref }}

      - name: Code quality checks
        run: bun run lerna run check --since ${{ github.event.pull_request.base.ref }}

This works for both main branch PRs and feature branches, as the base branch is used as the comparison basis. Only packages that have changed since the last commit on the base branch will be built and tested.

This would replace this code, where checks are run on all packages, regardless of what was changed.

ds25/.github/workflows/tag.yml

Lines 47 to 49 in ee6a5ef

	# TODO add Nx and only test the packages that have changed since last tag
	- name: Run tests
	run: bun run test

It would also require some modification to the environment setup action, which runs bun install instead of lerna bootstrap, causing an installation of dependencies and a build for all packages, instead of strictly necessary packages. That action should have a parameter added to use --ignore-scripts to avoid running the build script.

[jmuzina]

Looks like lerna bootstrap is not supported anymore. Lerna recommends using your package manager's install script to install dependencies, but this introduces a problem for us, since our prepare script at the root level also calls bun run build, building every package.

We should find a way to install dependencies (and automatically build, so that packages that depend on each other's build artifacts will not fail due to build artifacts not existing), while also building selectively using lerna --since.