public function testGetContextsDiff()
 {
     $user = new TestUser();
     $user->setId(1);
     $anotherUser = new TestUser();
     $anotherUser->setId(2);
     $thirdUser = new TestUser();
     $thirdUser->setId(3);
     $contexts = [$user, $anotherUser, $thirdUser];
     $otherContexts = [$user, $thirdUser];
     $result = $this->manager->getContextsDiff($contexts, $otherContexts);
     $this->assertEquals($result, [$anotherUser]);
     $contexts = ["one", "two", "three"];
     $otherContexts = ["two", "three"];
     $result = $this->manager->getContextsDiff($contexts, $otherContexts);
     $this->assertEquals($result, ["one"]);
 }