Add coverage workflow

Author: iv-craig

.github/workflows/coverage.yml

@@ -0,0 +1,32 @@
+name: Unit test coverage
+
+on:
+  - push
+  - pull_request
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    name: Unit test coverage
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 7.4
+          tools: composer:v2
+          coverage: pcov
+
+      - name: Install dependencies
+        run: composer update --prefer-stable --prefer-dist --no-interaction --no-progress
+
+      - name: Execute tests
+        run: vendor/bin/phpunit --verbose --coverage-text --coverage-clover=coverage.clover
+
+      - name: Send coverage to Scrutinizer
+        run: |
+          wget https://scrutinizer-ci.com/ocular.phar
+          php ocular.phar code-coverage:upload --format=php-clover coverage.clover