Add a positive test unit for _is_smiles when chem is none in test_compound_identifier.py

[Ajoke23]

…_identifier.py

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Description

Added a positive test for _is_smiles method when chem is none in the CompoundIdentifier class. The objective is to verify the
_is_smiles method in CompoundIdentifier class when Chem module is not available i.e when chem=None

Changes to be made

• Patched _pubchem_smiles_to_inchikey which is used for converting SMILES to InCHiKey when chem is none

• Mocked _pubchem_smiles_to_inchikey method to return "InchiKey" to simulate a valid InchiKey result. Therefore indicating SMILES input is valid

• Test with a Valid SMILES input. In this code, I used the valid SMILES string used is: CCO which represent Ethanol is passed to is_smiles method.

Status

Ran the test locally using pytest and it's passed all check. Proof: is_smiles - positive.log

To do

Awaiting mentors feedback

Is this pull request related to any open issue? If yes, replace issueID below with the issue ID

Related to #1319