Add test script to composer.json

Author: savamarkovic

composer.json

@@ -37,6 +37,9 @@
         "php": "^7.1 || ^8.0",
         "gmostafa/php-graphql-client": "^1.6 || ^2.0"
     },
+    "scripts": {
+        "test": "phpunit tests/ --whitelist src/ --coverage-clover build/coverage/xml"
+    },
     "require-dev": {
         "phpunit/phpunit": "^7.5|^8.0",
         "codacy/coverage": "^1.4",