Add phpstan check

.github/workflows/phpstan.yml

@@ -0,0 +1,32 @@
+name: PhpStan
+
+on:
+  push:
+    paths:
+      - "**.php"
+
+jobs:
+  phpstan:
+    name: phpstan
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "7.4"
+          extensions: dom, curl, libxml, mbstring, zip, pcntl, pdo, sqlite, pdo_sqlite, bcmath, soap, intl, gd, exif, iconv, imagick
+          coverage: none
+
+      - name: Cache composer dependencies
+        uses: actions/cache@v1
+        with:
+          path: vendor
+          key: composer-${{ hashFiles('composer.lock') }}
+
+      - name: Run composer require
+        run: composer require -n --prefer-dist
+
+      - name: Run phpstan
+        run: ./vendor/bin/phpstan analyze --level 2 src

composer.json

@@ -32,7 +32,8 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^4.0 || ^5.0 || ^8.0",
-        "orchestra/testbench": "^4.0"
+        "orchestra/testbench": "^4.0",
+        "phpstan/phpstan": "^0.12.56"
     },
     "autoload": {
         "psr-4": {