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

Master the art of Python decorators, from foundational concepts to advanced applications. This course guides you through the mechanics, use cases, and best practices of decorators, empowering you to write more expressive and reusable Python code.

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

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Challenge: Result Formatting Decorator

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