ci: add coveralls action

Author: Ffloriel

.github/workflows/build-and-test.yml

@@ -22,7 +22,11 @@ jobs:
         npm run bootstrap
         npm run build --if-present
         npm run lint
-        npm test
+        npm test -- --coverage
+    - name: Coveralls GitHub Action
+      uses: coverallsapp/github-action@1.1.3
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
       env:
         CI: true
 

packages/purgecss/README.md

@@ -4,6 +4,7 @@
 ![npm](https://img.shields.io/npm/dm/purgecss?style=for-the-badge)
 ![GitHub](https://img.shields.io/github/license/FullHuman/purgecss?style=for-the-badge)
 ![Dependabot](https://img.shields.io/badge/dependabot-enabled-%23024ea4?style=for-the-badge)
+[![Coverage Status](https://img.shields.io/coveralls/github/FullHuman/purgecss/main?style=for-the-badge)](https://coveralls.io/github/FullHuman/purgecss?branch=main)
 
 <p align="center">
 	<img src="https://i.imgur.com/UEiUiJ0.png" height="200" width="200" alt="PurgeCSS logo"/>