MAGE-1363 Remove legacy TestCase namespace (not used since M2.1)

Author: cammonro

Test/Integration/TestCase.php

@@ -19,13 +19,7 @@
 use Magento\Store\Model\ScopeInterface;
 use Magento\TestFramework\Helper\Bootstrap;
 
-if (class_exists('PHPUnit\Framework\TestCase')) {
-    class_alias('PHPUnit\Framework\TestCase', '\TC');
-} else {
-    class_alias('\PHPUnit_Framework_TestCase', '\TC');
-}
-
-abstract class TestCase extends \TC
+abstract class TestCase extends \PHPUnit\Framework\TestCase
 {
     /**
      * @var ObjectManagerInterface

composer.json

@@ -24,7 +24,8 @@
     }
   ],
   "require-dev": {
-    "phpcompatibility/php-compatibility": "^9.2"
+    "phpcompatibility/php-compatibility": "^9.2",
+    "phpunit/phpunit": "^9.5|^10.5"
   },
   "autoload": {
     "files": [ "registration.php" ],