Dye: add tests

[BvB93]

There are a number of examples of pre-existing tests already in CAT (ref).

[BvB93]

A quick test to see if two molecules are equivalent:

import numpy as np
from scm.plams import Molecule

mol1 = Molecule(...)
mol2 = Molecule(...)

def _get_atnum(mol: Molecule) -> np.ndarray:
    iterator = (at.atnum for at in mol)
    return np.fromiter(iterator, int, count=len(mol))

# check if the coords are the same
np.testing.assert_allclose(mol1, mol2)  

# check if atomic symbols/numbers are the same
np.testing.assert_array_equal(_get_atnum(mol1), _get_atnum(mol2))  

# Check if the bonds are the same
np.testing.assert_allclose(mol1.bond_matrix(), mol2.bond_matrix())