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

class TestTask(unittest.TestCase):
    def test_correct_substring(self):
        import user_code
        importlib.reload(user_code)
        result = user_code.substring_between_chars("abracadabra", "a")
        _dynamic_test(
            self,
            result == "bracadabr",
            "Returns correct substring when char appears more than once.",
            f"Expected 'bracadabr', got '{result}'.",
        )

    def test_only_one_occurrence(self):
        import user_code
        importlib.reload(user_code)
        result = user_code.substring_between_chars("test", "e")
        _dynamic_test(
            self,
            result == "",
            "Returns empty string when char appears only once.",
            f"Expected empty string, got '{result}'.",
        )

    def test_no_occurrence(self):
        import user_code
        importlib.reload(user_code)
        result = user_code.substring_between_chars("test", "x")
        _dynamic_test(
            self,
            result == "",
            "Returns empty string when char does not appear.",
            f"Expected empty string, got '{result}'.",
        )

    def test_empty_between(self):
        import user_code
        importlib.reload(user_code)
        result = user_code.substring_between_chars("aba", "b")
        _dynamic_test(
            self,
            result == "",
            "Returns empty string when nothing is between first and last occurrence.",
            f"Expected empty string, got '{result}'.",
        )

    def test_sample_case_2(self):
        import user_code
        importlib.reload(user_code)
        result = user_code.substring_between_chars("hello world", "l")
        _dynamic_test(
            self,
            result == "lo wor",
            "Returns correct substring for sample case 2.",
            f"Expected 'lo wor', 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()
    for i, node in enumerate(tree.body):
        if isinstance(node, ast.Assign):
            for target in node.targets:
                if isinstance(target, ast.Name) and target.id == var_name:
                    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] = []
                    
                    return '\\n'.join(lines)
    return code

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


test_main.py

A beginner-friendly course focused on mastering string manipulation and handling various data formats in Python. Learn essential techniques for processing, formatting, and converting data, with hands-on practice and quizzes to reinforce your understanding.

Learn the core techniques for working with strings in Python, including slicing, searching, and modifying text.

Develop skills for formatting strings and converting between data types for effective data presentation and processing.

Gain practical experience handling structured data formats such as CSV and JSON using Python's built-in capabilities.

Challenge: String Slicing and Indexing

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Challenge: String Slicing and Indexing

Solution