test: configure PHPUnit coverage filter

Author: overtrue

phpunit.xml.dist

@@ -1,6 +1,19 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" backupGlobals="false" bootstrap="vendor/autoload.php" colors="true" processIsolation="false" stopOnFailure="false" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.2/phpunit.xsd" cacheDirectory=".phpunit.cache" backupStaticProperties="false">
-  <coverage/>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         backupGlobals="false"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+         processIsolation="false"
+         stopOnFailure="false"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/12.5/phpunit.xsd"
+         cacheDirectory=".phpunit.cache"
+         backupStaticProperties="false">
+  <coverage>
+    <include>
+      <directory suffix=".php">./src</directory>
+    </include>
+  </coverage>
+
   <testsuites>
     <testsuite name="Application Test Suite">
       <directory>./tests/</directory>