workflow-files | common webpack , rollup , gulp config files | Plugin library

According to the official GitHub Actions documentation (About workflow events):

The following steps occur to trigger a workflow run:

1. An event occurs on your repository, and the resulting event webhook has an associated commit SHA and Git ref.

2. The .github/workflows directory in your repository is searched for workflow files at the associated commit SHA or Git ref. The workflow files must be present in that commit SHA or Git ref to be considered.
   
   For example, if the event occurred on a particular repository branch, then the workflow files must be present in the repository on that branch.

3. The workflow files for that commit SHA and Git ref are inspected, and a new workflow run is triggered for any workflows that have on: values that match the triggering event.
   
   The workflow runs on your repository's code at the same commit SHA and Git ref that triggered the event. When a workflow runs, GitHub sets the GITHUB_SHA (commit SHA) and GITHUB_REF (Git ref) environment variables in the runner environment. For more information, see "Using environment variables."

Because of this, in order to test the workflows we need to perform a git action (ie. do push) in the created branch.