Add phpstan PHP Static Analysis Tool

.gitignore

@@ -3,3 +3,4 @@ composer.phar
 composer.lock
 vendor/
 bin/
+phpstan.phar

.travis.yml

@@ -9,7 +9,13 @@ php:
     - 7.2
     - nightly
 
-matrix:
+jobs:
+    include:
+        - stage: Code Quality
+          php: 7.2
+          env: STATIC_ANALYSIS
+          install: travis_retry composer install --prefer-dist
+          script: composer static-analysis
     allow_failures:
         - php: nightly
 

composer.json

@@ -18,9 +18,6 @@
   },
   "config": {
     "bin-dir": "bin",
-    "platform": {
-      "php": "5.6.0"
-    },
     "preferred-install": "dist",
     "sort-packages": true
 },
@@ -36,6 +33,15 @@
       "GraphQL\\Examples\\Blog\\": "examples/01-blog/Blog/"
     }
   },
+  "scripts": {
+    "static-analysis": [
+      "rm phpstan.phar || true",
+      "@composer req --ansi --no-interaction --dev phpstan/phpstan-shim",
+      "cp -f vendor/phpstan/phpstan-shim/phpstan.phar .",
+      "@composer rem --ansi --dev phpstan/phpstan-shim",
+      "@php phpstan.phar analyse --ansi -l 1 -c phpstan.neon src"
+    ]
+  },
   "suggest": {
     "react/promise": "To leverage async resolving on React PHP platform",
     "psr/http-message": "To use standard GraphQL server"