Update PHPUnit configuration: upgrade schema to 12.5, enforce stricter checks

Author: qzminski

.github/workflows/ci.yml

@@ -34,5 +34,4 @@ jobs:
               run: COMPOSER_MEMORY_LIMIT=-1 composer install --dev --no-interaction
 
             - name: Run tests
-              run: |
-                  php vendor/bin/phpunit
+              run: composer run unit-tests

phpunit.xml.dist

@@ -1,15 +1,23 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd" colors="true" bootstrap="tests/bootstrap.php">
-  <php>
-    <ini name="error_reporting" value="-1"/>
-    <ini name="display_errors" value="1"/>
-    <ini name="display_startup_errors" value="1"/>
-  </php>
-  <testsuites>
-    <testsuite name="Unit Tests">
-      <directory>./tests</directory>
-      <exclude>./tests/Fixtures</exclude>
-    </testsuite>
-  </testsuites>
-  <logging/>
+<phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/12.5/phpunit.xsd"
+    bootstrap="tests/bootstrap.php"
+    colors="true"
+    failOnWarning="true"
+    failOnRisky="true"
+    beStrictAboutTestsThatDoNotTestAnything="true"
+>
+    <php>
+        <ini name="error_reporting" value="-1"/>
+        <ini name="display_errors" value="1"/>
+        <ini name="display_startup_errors" value="1"/>
+    </php>
+
+    <testsuites>
+        <testsuite name="Unit Tests">
+            <directory>tests</directory>
+            <exclude>tests/Fixtures</exclude>
+        </testsuite>
+    </testsuites>
 </phpunit>