Add a positive test unit for _is_smiles when chem is none in test_com…

…pound_identifier.py (#1332)

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

* Test for valid SMILES input

---------

Co-authored-by: Dhanshree Arora <[email protected]>

test/test_compound_identifier.py

@@ -1,5 +1,6 @@
 import pytest
 from ersilia.utils.identifiers.compound import CompoundIdentifier
+from unittest.mock import patch
 
 @pytest.fixture
 def compound_identifier():
@@ -18,8 +19,17 @@ def test_is_input_header_negative(compound_identifier, header):
 def test_is_key_header_positive(compound_identifier, header):
     """Test that valid key headers return True."""
     assert compound_identifier.is_key_header(header) is True
-
+    
 @pytest.mark.parametrize("header", ["id","smiles","inchi","input", "some_header", "random", "header", ""])
 def test_is_key_header_negative(compound_identifier, header):
     assert not compound_identifier.is_key_header(header)
+
+@patch('ersilia.utils.identifiers.compound.CompoundIdentifier._pubchem_smiles_to_inchikey')
+def test_is_smiles_positive_chem_none(mock_pubchem, compound_identifier):
+    compound_identifier.Chem = None
+    mock_pubchem.return_value = "InChIKey"
 
+# Test with a valid SMILES input
+    smiles_string = 'CCO' #Ethanol SMILES
+    assert compound_identifier._is_smiles(smiles_string) is True
+