test: add test for get same config with different alias

If the request class is the same, it is better to return the shared
instance.

Author: kenjis

tests/system/Config/FactoriesTest.php

@@ -12,6 +12,7 @@
 namespace CodeIgniter\Config;
 
 use CodeIgniter\Test\CIUnitTestCase;
+use Config\App;
 use Config\Database;
 use InvalidArgumentException;
 use ReflectionClass;
@@ -322,6 +323,14 @@ public function testCanLoadTwoCellsWithSameShortName()
         $this->assertNotSame($cell1, $cell2);
     }
 
+    public function testCanLoadSharedConfigWithDifferentAlias()
+    {
+        $config1 = Factories::config(App::class);
+        $config2 = Factories::config('App');
+
+        $this->assertSame($config1, $config2);
+    }
+
     public function testDefineSameAliasTwiceWithDifferentClasses()
     {
         $this->expectException(InvalidArgumentException::class);