def METHOD_NAME(self):
    """
    test that all particles in the polymer are connected by pushing one particle
    """
    self.system.part.by_id(
        self.diamond_params['start_id']).ext_force = 3 * [2]
    self.system.integrator.run(200)
    vels = np.linalg.norm(self.system.part.all().v, axis=1)
    self.assertGreater(np.min(vels), 1e-6)