#271 Reorder phpunit env var and use server instead env

see https://github.com/laravel/laravel/blob/06162adc9839ada8b2525e006bef6b80914296d6/phpunit.xml

phpunit.xml

@@ -22,17 +22,18 @@
     </testsuites>
     <filter>
         <whitelist processUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">./app</directory>
+            <directory suffix=".php">./src</directory>
         </whitelist>
     </filter>
     <php>
-        <env name="APP_ENV" value="testing"/>
-        <env name="DEBUGBAR_ENABLED" value="false"/>
-        <env name="BCRYPT_ROUNDS" value="4"/>
-        <env name="DB_CONNECTION" value="testing"/>
-        <env name="CACHE_DRIVER" value="array"/>
-        <env name="QUEUE_CONNECTION" value="null"/>
-        <env name="MAIL_DRIVER" value="array"/>
-        <env name="SESSION_DRIVER" value="array"/>
+        <server name="APP_ENV" value="testing"/>
+        <server name="BCRYPT_ROUNDS" value="4"/>
+        <server name="CACHE_DRIVER" value="array"/>
+        <server name="MAIL_DRIVER" value="array"/>
+        <server name="QUEUE_CONNECTION" value="null"/>
+        <server name="SESSION_DRIVER" value="array"/>
+
+        <server name="DB_CONNECTION" value="testing"/>
+        <server name="DEBUGBAR_ENABLED" value="false"/>
     </php>
 </phpunit>