Add test suite for core module.

tools/phpunit/phpunit.xml

@@ -16,10 +16,14 @@
         <testsuite name="Metadata">
             <directory>./../../tests/Metadata/</directory>
         </testsuite>
+        <testsuite name="modules-core">
+            <directory>./../../tests/modules/core/</directory>
+        </testsuite>
     </testsuites>
     <filter>
         <whitelist processUncoveredFilesFromWhitelist="true">
             <directory suffix=".php">./../../lib/</directory>
+            <directory suffix=".php">./../../modules/core/lib/</directory>
             <exclude>
                 <directory>./../../vendor/</directory>
                 <directory>./../../tests/</directory>