Update PHPUnit

Author: kylekatarnls

.github/workflows/tests.yml

@@ -46,8 +46,7 @@ jobs:
     - name: Install dependencies
       if: steps.composer-cache.outputs.cache-hit != 'true'
       run: |
-        ${{ matrix.php >= 8.1 && 'composer require --no-update phpunit/phpunit:^8.5.14 --no-interaction' || '' }}
-        composer update --prefer-dist ${{ matrix.setup != 'next' && matrix.setup != 'no-calendar' && format('--prefer-{0}', matrix.setup) || '' }} --no-progress --no-suggest ${{ matrix.php >= 8.1 && '--ignore-platform-req=php' || '' }}
+        composer update --prefer-dist ${{ matrix.setup != 'next' && matrix.setup != 'no-calendar' && format('--prefer-{0}', matrix.setup) || '' }} --no-progress --no-suggest
 
     - name: Fix PHP compatibility
       if: matrix.php >= '8.1'

phpunit.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
+         bootstrap="tests/bootstrap.php"
+         cacheDirectory=".phpunit.cache"
+         executionOrder="depends,defects"
+         beStrictAboutOutputDuringTests="true"
+         displayDetailsOnPhpunitDeprecations="true"
+         failOnPhpunitDeprecation="true"
+         failOnRisky="true"
+         failOnWarning="true">
+    <testsuites>
+        <testsuite name="default">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+
+    <source restrictDeprecations="true" restrictNotices="true" restrictWarnings="true">
+        <include>
+            <directory>src/Cmixin</directory>
+        </include>
+    </source>
+
+    <!-- Backward compatibility -->
+    <filter>
+        <whitelist>
+            <directory>src/Cmixin</directory>
+        </whitelist>
+    </filter>
+</phpunit>