def METHOD_NAME(self):
    density_profile = espressomd.observables.ForceDensityProfile(
        **self.kwargs)
    self.system.part.all().ext_force = [0.0, 0.0, 1.0]
    self.system.integrator.run(0)
    obs_data = density_profile.calculate()
    np.testing.assert_array_equal(
        obs_data.shape, [self.kwargs['n_x_bins'], self.kwargs['n_y_bins'],
                         self.kwargs['n_z_bins'], 3])
    self.assertEqual(obs_data[0, 0, 1, 2], 2.0 / self.bin_volume)
    self.assertEqual(obs_data[1, 1, 3, 2], 1.0 / self.bin_volume)
    self.assertEqual(np.sum(np.abs(obs_data)), 3.0 / self.bin_volume)