def test_has_edge():
"""Test that the right edges exist."""
carb = AtomSpec('C')
hyd = AtomSpec('H')
atoms = [carb, hyd, hyd, carb, hyd]
bonds = [
BondSpec(0, 1, 1),
BondSpec(0, 2, 1),
BondSpec(0, 3, 2),
BondSpec(3, 4, 1),
]
molecule = Molecule(atoms, bonds)
assert molecule.has_edge(0, 3)
def test_has_edge():
"""Test that ``has_edge`` returns the correct result."""
molecule = Molecule([], [])
with pytest.raises(ValueError):
molecule.has_edge(0, 1)