import unittest
import importlib
import io
import ast
import re
from contextlib import redirect_stdout

# ── helpers ───────────────────────────────────────────────────────────────────

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

# ── tests ─────────────────────────────────────────────────────────────────────

class TestTask(unittest.TestCase):
    def setUp(self):
        """Чистый импорт user_code с гашением его print при импорте."""
        import sys
        if "user_code" in sys.modules:
            del sys.modules["user_code"]
        buf = io.StringIO()
        with redirect_stdout(buf):
            import user_code  # noqa: F401
        self.import_output = buf.getvalue()
        self.mod = importlib.import_module("user_code")

    def test_import_prints_expected_lines(self):
        txt = normalize_text(self.import_output)
        ok1 = "hello, alice!" in txt
        ok2 = "goodbye, bob." in txt
        _dynamic_test(
            self,
            ok1 and ok2,
            "module prints uppercase lines at import",
            f"Import output mismatch. Got: {self.import_output!r}",
        )

    def test_greet_uppercase(self):
        result = self.mod.greet("Alice")
        _dynamic_test(
            self,
            result == "HELLO, ALICE!",
            "greet returns uppercase string result",
            f"Expected 'HELLO, ALICE!', got '{result}'",
        )

    def test_farewell_uppercase(self):
        result = self.mod.farewell("Bob")
        _dynamic_test(
            self,
            result == "GOODBYE, BOB.",
            "farewell returns uppercase string result",
            f"Expected 'GOODBYE, BOB.', got '{result}'",
        )

    def test_non_string_result_unmodified(self):
        # добавим функцию, которая возвращает число, и задекорируем её тем же декоратором из user_code
        code = ""
        with open("user_code.py", "r", encoding="utf-8") as f:
            code = f.read()
        code += "\\n@uppercase_result\\ndef add(a, b):\\n    return a + b\\n"
        ns = {}
        exec(code, ns)
        result = ns["add"](3, 4)
        _dynamic_test(
            self,
            result == 7,
            "decorator returns non-string result unchanged",
            f"Expected 7, got {result}",
        )

    def test_multiple_functions(self):
        # проверим, что декоратор стабильно работает на нескольких функциях
        code = ""
        with open("user_code.py", "r", encoding="utf-8") as f:
            code = f.read()
        code += (
            "\\n@uppercase_result\\ndef hello():\\n    return 'hi'\\n"
            "@uppercase_result\\ndef bye():\\n    return 'bye'\\n"
        )
        ns = {}
        exec(code, ns)
        r1 = ns["hello"]()
        r2 = ns["bye"]()
        _dynamic_test(
            self,
            r1 == "HI" and r2 == "BYE",
            "decorator works correctly for multiple functions",
            f"Expected 'HI' and 'BYE', got '{r1}' and '{r2}'",
        )

if __name__ == "__main__":
    unittest.main(verbosity=2)


test_main.py

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Explore the foundational concepts of Python decorators, including their syntax, how they work, and why they're useful.

Delve deeper into decorators by exploring arguments, chaining, and built-in decorators.

Explore Python's built-in decorators and practical use cases for custom decorators.

Apply your knowledge of decorators in a series of hands-on coding challenges.

Challenge: Result Formatting Decorator

Solution