Phpunit 5 requires a whitelist, not a blacklist

phpunit.xml.dist

@@ -34,15 +34,10 @@
 
     <!-- Prevent coverage reports from looking in tests, vendors, config folders -->
     <filter>
-        <blacklist>
-            <directory suffix=".php">./vendor/</directory>
-            <directory suffix=".ctp">./vendor/</directory>
-
-            <directory suffix=".php">./tests/</directory>
-            <directory suffix=".ctp">./tests/</directory>
-
-            <directory suffix=".php">./config/</directory>
-        </blacklist>
+        <whitelist>
+            <directory suffix=".php">./src/</directory>
+            <directory suffix=".ctp">./src/</directory>
+        </whitelist>
     </filter>
 
     <php>