def test_onetep(testdir):
    from ase.build import molecule
    from ase.calculators.onetep import Onetep
    from os.path import isfile, join

    mol = molecule('H2O')
    mol.center(8)
    calc = Onetep(label='water')
    # Tests conducted with the JTH PAW data set.
    # http://www.abinit.org/downloads/PAW2
    prefix = 'hello'
    h_path = join(prefix, 'H.abinit')
    o_path = join(prefix, 'O.abinit')
    if not (isfile(h_path) and isfile(o_path)):
        raise Exception("""You must supply PAW data sets for
            hydrogen and oxygen to run this test.
            Please see http://www.abinit.org/downloads/PAW2
            for suitable data. ONETEP takes PAW data sets in the
            abinit format. I need H.abinit and O.abinit""")
    calc.set_pseudos([('H', h_path), ('O', o_path)])
    calc.set(paw=True, xc='PBE', cutoff_energy='400 eV')
    mol.calc = calc

    energy = mol.get_total_energy()
    ref_energy = -470.852068717
    assert abs(energy - ref_energy) < 1e-6
