Set up GitHub Actions

.github/workflows/tests.yml

@@ -0,0 +1,43 @@
+name: Tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  tests:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '7.2'
+          tools: phpunit:9,psalm
+
+      - name: Setup problem matchers for PHPUnit
+        run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+
+      - name: Get composer cache directory
+        id: composercache
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache dependencies
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.composercache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: ${{ runner.os }}-composer-
+
+      - run: composer install --no-interaction
+
+      - name: Psalm
+        run: psalm --output-format=github
+        if: always()
+
+      - name: PHPUnit
+        run: phpunit --coverage-text
+        if: always()