test: add 100% coverage with codecov integration

Author: jamesbechet

.github/workflows/ci.yml

@@ -24,5 +24,11 @@ jobs:
       - name: Install
         run: npm ci
 
-      - name: Test
-        run: npm test
+      - name: Test with coverage
+        run: npm run test:coverage -- --coverageThreshold='{"global":{"branches":100,"functions":100,"lines":100,"statements":100}}' --coverageReporters=json-summary
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          fail_ci_if_error: false

README.md

@@ -1,6 +1,7 @@
 # Element Picker – JavaScript HTML Element Picker Library
 
 ![CI](https://github.com/jamesbechet/element-picker/actions/workflows/ci.yml/badge.svg)
+[![codecov](https://codecov.io/gh/jamesbechet/element-picker/branch/master/graph/badge.svg)](https://codecov.io/gh/jamesbechet/element-picker)
 [![npm][npm-image]][npm-url] [![downloads][downloads-image]][downloads-url]
 
 [npm-image]: https://img.shields.io/npm/v/element-picker.svg