Add GitHub Actions workflow

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: PHP Composer
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  # Based on https://github.com/nanasess/setup-php
+  tests:
+    runs-on: ${{ matrix.operating-system }}
+    strategy:
+      matrix:
+        operating-system: [ ubuntu-latest, windows-latest ]
+        php: [ '7.3', '7.4', '8.0' ]
+    name: PHP ${{ matrix.php }} tests (${{ matrix.operating-system }})
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup PHP
+        uses: nanasess/setup-php@master
+        with:
+          php-version: ${{ matrix.php }}
+
+      - name: Validate composer.json and composer.lock
+        run: composer validate
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v2
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-
+
+      - name: Install dependencies
+        if: steps.composer-cache.outputs.cache-hit != 'true'
+        run: composer install --prefer-dist --no-progress --no-suggest
+
+      - name: Run tests
+        run: composer run-script tests

composer.json

@@ -35,5 +35,8 @@
     "platform": {
       "php": "7.3.0"
     }
+  },
+  "scripts": {
+    "tests": "php vendor/bin/phpunit"
   }
 }