MC-24726: Plugins are dismissed for virtual type parents in developer mode

- add unit test

Author: krissyhiserote

lib/internal/Magento/Framework/Interception/Test/Unit/ObjectManager/Config/DeveloperTest.php

@@ -58,4 +58,23 @@ public function testGetOriginalInstanceTypeReturnsInterceptedClass()
         $this->assertEquals('SomeClass\Interceptor', $this->model->getInstanceType('SomeClass'));
         $this->assertEquals('SomeClass', $this->model->getOriginalInstanceType('SomeClass'));
     }
+
+    /**
+     * Test correct instance type is returned when plugins are created for virtual type parents
+     *
+     * @return void
+     */
+    public function testGetInstanceTypeWithPluginOnVirtualTypeParent() : void
+    {
+        $reflectionClass = new \ReflectionClass(get_class($this->model));
+        $reflectionProperty = $reflectionClass->getProperty('_virtualTypes');
+        $reflectionProperty->setAccessible(true);
+        $reflectionProperty->setValue($this->model, ['SomeVirtualClass' => 'SomeClass']);
+
+        $this->interceptionConfig->expects($this->once())->method('hasPlugins')->with('SomeClass')->willReturn(true);
+        $this->model->setInterceptionConfig($this->interceptionConfig);
+
+        $instanceType = $this->model->getInstanceType('SomeVirtualClass');
+        $this->assertEquals('SomeClass\Interceptor', $instanceType);
+    }
 }