def test__add_atom():
""" test zmat.add_atom
output below should look like this:
C
O 1 R2
C 2 R3 1 A3
H 3 R4 2 A4 1 D4
H 3 R5 2 A5 1 D5
H 3 R6 2 A6 1 D6
R2 = 1.500000
R3 = 1.500000
R4 = 1.500000
R5 = 1.500000
R6 = 1.500000
A3 = 120.000000
A4 = 120.000000
A5 = 120.000000
A6 = 120.000000
D4 = 0.000000
D5 = 109.470000
D6 =-109.470000
"""
zma = ()
zma = zmat.add_atom(zma, 'C', (), ())
zma = zmat.add_atom(zma, 'O', (0, ), (1.5, ))
zma = zmat.add_atom(zma, 'C', (1, 0), (1.5, 120.))
zma = zmat.add_atom(zma, 'H', (2, 1, 0), (1.5, 120., 0.))
zma = zmat.add_atom(zma, 'H', (2, 1, 0), (1.5, 120., +109.47))
zma = zmat.add_atom(zma, 'H', (2, 1, 0), (1.5, 120., -109.47))
print(zmat.string(zma))
def test__string():
""" test zmat.string
"""
zma = zmat.from_string(zmat.string(CH4O2_ZMA))
assert zmat.almost_equal(zma, CH4O2_ZMA)