def test_user_cannot_create_existing_array():
reference = Molecule(atoms)
reference.new_array("symbol", ["H", "H", "C"])
with pytest.raises(Exception) as error:
reference.new_array("symbol", ["H", "H", "C"])
assert error.value.args[0] == 'Array "symbol" already present'
def test_user_cannot_create_array_with_different_size():
reference = Molecule(atoms)
with pytest.raises(Exception) as error:
reference.new_array("symbol", [])
assert error.value.args[0] == 'Array "symbol" has wrong length: 0 != 3.'