Add PHPStan to test environment with max level

.gitattributes

@@ -2,6 +2,7 @@
 /.github/ export-ignore
 /.gitignore export-ignore
 /examples/ export-ignore
+/phpstan.neon.dist export-ignore
 /phpunit.xml.dist export-ignore
 /phpunit.xml.legacy export-ignore
 /tests/ export-ignore

.github/workflows/ci.yml

@@ -52,3 +52,25 @@ jobs:
       - run: docker run -d --name mysql --net=host -e MYSQL_RANDOM_ROOT_PASSWORD=yes -e MYSQL_DATABASE=test -e MYSQL_USER=test -e MYSQL_PASSWORD=test mysql:5
       - run: bash tests/wait-for-mysql.sh
       - run: docker run -i --rm --workdir=/data -v "$(pwd):/data" --net=host hhvm/hhvm:3.30-lts-latest hhvm vendor/bin/phpunit
+
+  PHPStan:
+    name: PHPStan (PHP ${{ matrix.php }})
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        php:
+          - 8.2
+          - 8.1
+          - 8.0
+          - 7.4
+          - 7.3
+          - 7.2
+          - 7.1
+    steps:
+      - uses: actions/checkout@v3
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: none
+      - run: composer install
+      - run: vendor/bin/phpstan

README.md

@@ -455,6 +455,12 @@ To run the test suite, go to the project root and run:
 vendor/bin/phpunit
 ```
 
+On top of this, we use PHPStan on max level to ensure type safety across the project:
+
+```bash
+vendor/bin/phpstan
+```
+
 ## License
 
 MIT, see [LICENSE file](LICENSE).

composer.json

@@ -13,6 +13,7 @@
         "react/socket": "^1.12"
     },
     "require-dev": {
+        "phpstan/phpstan": "1.10.20 || 1.4.10",
         "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36",
         "react/async": "^4 || ^3 || ^2"
     },

phpstan.neon.dist

@@ -0,0 +1,6 @@
+parameters:
+  level: max
+
+  paths:
+    - src/
+    - tests/

src/MysqlClient.php

@@ -8,6 +8,7 @@
 use React\Mysql\Io\Factory;
 use React\Promise\Deferred;
 use React\Promise\Promise;
+use React\Promise\PromiseInterface;
 use React\Socket\ConnectorInterface;
 use React\Stream\ReadableStreamInterface;