public function testUser()
 {
     $businessUnit = new BusinessUnit();
     $user = new User();
     $businessUnit->setUsers(new ArrayCollection(array($user)));
     $this->assertContains($user, $businessUnit->getUsers());
     $businessUnit->removeUser($user);
     $this->assertNotContains($user, $businessUnit->getUsers());
     $businessUnit->addUser($user);
     $this->assertContains($user, $businessUnit->getUsers());
 }