def METHOD_NAME(self):
    """
    Test integration of density on real space grid.
    The integral of the density of the real space grid should yield the
    number of electrons.
    """
    # Create a calculator.
    dens_calculator = Density(test_parameters)
    dens_calculator.read_additional_calculation_data(path_to_out,
                                                     "espresso-out")
    # Read the input data.
    density_dft = np.load(path_to_dens_npy)
    # Calculate the quantities we want to compare.
    nr_mala = dens_calculator.get_number_of_electrons(density_dft)
    nr_dft = dens_calculator.number_of_electrons_exact
    # Calculate relative error.
    rel_error = np.abs(nr_mala-nr_dft) / nr_dft
    printout("Relative error number of electrons: ", rel_error,
             min_verbosity=0)
    # Check against the constraints we put upon ourselves.
    assert np.isclose(rel_error, 0, atol=accuracy)