Add PHPStan analysis (#45)

* [wpmlbridge-296] Bring PHPStan analysis.

https://onthegosystems.myjetbrains.com/youtrack/issue/wpmlbridge-296

.github/workflows/php.yml

@@ -1,5 +1,5 @@
-name: OTGS PHP UNIT
-run-name: PHP Unit at ${{ github.ref_name }}
+name: OTGS PHP TEST
+run-name: PHP TEST at ${{ github.ref_name }}
 
 on: [push, pull_request]
 
@@ -20,5 +20,8 @@ jobs:
       - name: Install dependencies
         run: composer install --prefer-dist --no-progress --no-suggest
 
-      - name: Run test suite
+      - name: Run unit test suite
         run: ./vendor/bin/phpunit
+
+      - name: Run static test suite
+        run: ./vendor/bin/phpstan

composer.json

@@ -28,22 +28,26 @@
     "config": {
         "sort-packages": true,
         "platform": {
-            "php": "5.6"
+            "php": "7.4"
         },
         "allow-plugins": {
-            "dealerdirect/phpcodesniffer-composer-installer": true
+            "dealerdirect/phpcodesniffer-composer-installer": true,
+            "phpstan/extension-installer": true
         }
     },
     "minimum-stability": "dev",
     "prefer-stable": true,
     "require-dev": {
-        "roave/security-advisories": "dev-master",
+        "dealerdirect/phpcodesniffer-composer-installer": "*",
         "otgs/unit-tests-framework": "~1.2.0",
-        "sebastian/phpcpd": "^3.0",
-        "squizlabs/php_codesniffer": "~3",
         "phpcompatibility/php-compatibility": "*",
         "phpcompatibility/phpcompatibility-wp": "*",
-        "dealerdirect/phpcodesniffer-composer-installer": "*",
+        "phpstan/extension-installer": "^1.3",
+        "phpstan/phpstan": "^1.10",
+        "roave/security-advisories": "dev-master",
+        "sebastian/phpcpd": "^3.0",
+        "squizlabs/php_codesniffer": "~3",
+        "szepeviktor/phpstan-wordpress": "^1.3",
         "wp-coding-standards/wpcs": "^0"
     },
     "scripts": {