
import unittest
import user_code
import ast
import re   
import importlib
import csv
import unittest
import user_code
import ast
import re   
import importlib

class TestTask(unittest.TestCase):
    def test_returns_correct_count_for_examples(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, 'count_atoms_in_smiles', None)
        _dynamic_test(self, func is not None, 'Function count_atoms_in_smiles exists', 'Function count_atoms_in_smiles not found')
        if func is None:
            return
        test_cases = [
            ("CCO", 3),
            ("C1=CC=CC=C1", 6),
            ("ClCBr", 3),
            ("CC(=O)O", 4),
        ]
        for smiles, expected in test_cases:
            result = func(smiles)
            _dynamic_test(self, result == expected, f"Returns {expected} for '{smiles}'", f"Expected {expected} for '{smiles}', got {result}")

    def test_two_letter_atoms(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, 'count_atoms_in_smiles', None)
        _dynamic_test(self, func is not None, 'Function count_atoms_in_smiles exists', 'Function count_atoms_in_smiles not found')
        if func is None:
            return
        # "ClBr" should count as 2 atoms (Cl, Br)
        result = func("ClBr")
        _dynamic_test(self, result == 2, 'Correctly counts two-letter atom symbols', f"Expected 2 for 'ClBr', got {result}")

    def test_ignores_digits_bonds(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, 'count_atoms_in_smiles', None)
        _dynamic_test(self, func is not None, 'Function count_atoms_in_smiles exists', 'Function count_atoms_in_smiles not found')
        if func is None:
            return
        # "C1=CC(=O)O" should count as 5 (C, C, C, O, O)
        result = func("C1=CC(=O)O")
        _dynamic_test(self, result == 5, 'Ignores digits, bonds, and parentheses', f"Expected 5 for 'C1=CC(=O)O', got {result}")

    def test_empty_string(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, 'count_atoms_in_smiles', None)
        _dynamic_test(self, func is not None, 'Function count_atoms_in_smiles exists', 'Function count_atoms_in_smiles not found')
        if func is None:
            return
        result = func("")
        _dynamic_test(self, result == 0, 'Returns 0 for empty SMILES string', f"Expected 0 for empty string, got {result}")

def _dynamic_test(test_case, condition, success_message, failure_message):
    if condition:
        test_case._testMethodName = success_message
        test_case.assertTrue(True, success_message)
    else:
        test_case._testMethodName = failure_message
        test_case.fail(failure_message)

def normalize_text(text):
    text = text.lower()
    text = re.sub(r"\\s{2,}", " ", text)
    text = re.sub(r"\\s*([,:?])\\s*", r"\\1 ", text)
    return text.strip()

def change_var(code: str, var_name: str, value: str) -> str:
    tree = ast.parse(code)
    lines = code.splitlines()
    changed = False
    # Collect all assignment nodes to modify
    assign_nodes = [
        (i, node)
        for i, node in enumerate(tree.body)
        if isinstance(node, ast.Assign)
        and any(isinstance(target, ast.Name) and target.id == var_name for target in node.targets)
    ]

    # If nothing to change, return unmodified code
    if not assign_nodes:
        return code

    # Perform replacements for all matching assignments (from last to first to not break line offsets)
    for i, node in reversed(assign_nodes):
        start_line = node.lineno - 1
        line = lines[start_line]
        indent = ' ' * (len(line) - len(line.lstrip()))
        lines[start_line] = f"{indent}{var_name} = {value}"
        next_line = len(lines)
        for next_node in tree.body[i+1:]:
            if hasattr(next_node, 'lineno'):
                next_line = next_node.lineno - 1
                break
        if next_line > start_line + 1:
            lines[start_line+1:next_line] = []
        changed = True

    return '\\n'.join(lines) if changed else code

if __name__ == "__main__":
    unittest.main()


test_main.py

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Explore how molecules are represented digitally and learn to parse and interpret these representations using Python.

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Apply chemoinformatics techniques to screen and rank compound libraries for drug discovery.

Challenge: Parse SMILES Strings

Solution

Challenge: Parse SMILES Strings

Solution