Segregate legacy method test

We would not want to mark the whole test as legacy.

tests/Doctrine/Tests/ORM/Decorator/EntityManagerDecoratorTest.php

@@ -35,7 +35,7 @@ public function getMethodParameters()
         $methods = [];
 
         foreach ($class->getMethods() as $method) {
-            if ($method->isConstructor() || $method->isStatic() || !$method->isPublic()) {
+            if ($method->isConstructor() || $method->isStatic() || !$method->isPublic() || $method->getName() === 'getHydrator') {
                 continue;
             }
 
@@ -84,4 +84,20 @@ public function testAllMethodCallsAreDelegatedToTheWrappedInstance($method, arra
 
         $this->assertSame($return, $decorator->$method(...$parameters));
     }
+
+    /**
+     * @group legacy
+     */
+    public function testGetHydratorCallIsDelegatedToTheWrappedInstance()
+    {
+        $this->wrapped->expects($this->once())
+            ->method('getHydrator')
+            ->with([$mode = 'some random mode'])
+            ->willReturn($return = 'INNER VALUE FROM getHydrator');
+
+        $decorator = new class ($this->wrapped) extends EntityManagerDecorator {
+        };
+
+        $this->assertSame($return, $decorator->getHydrator([$mode]));
+    }
 }