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

class TestTask(unittest.TestCase):
    def test_prints_only_txt_files(self):
        import user_code
        importlib.reload(user_code)
        files = ["a.txt", "b.docx", "c.txt", "d.pdf", "e.txt"]
        f = io.StringIO()
        with redirect_stdout(f):
            user_code.filter_txt_files(files)
        output = normalize_text(f.getvalue())
        expected = ["a.txt", "c.txt", "e.txt"]
        for name in expected:
            _dynamic_test(
                self,
                normalize_text(name) in output,
                f"'{name}' is printed as expected",
                f"Expected '{name}' to be printed, got: {output}",
            )
        # Ensure non .txt files are not printed
        not_expected = ["b.docx", "d.pdf"]
        for name in not_expected:
            _dynamic_test(
                self,
                normalize_text(name) not in output,
                f"'{name}' is not printed as expected",
                f"Did not expect '{name}' to be printed, got: {output}",
            )

    def test_no_txt_files(self):
        import user_code
        importlib.reload(user_code)
        files = ["a.pdf", "b.docx", "c.xlsx"]
        f = io.StringIO()
        with redirect_stdout(f):
            user_code.filter_txt_files(files)
        output = normalize_text(f.getvalue())
        _dynamic_test(
            self,
            output.strip() == "",
            "No output when there are no .txt files",
            f"Expected no output, got: {output}",
        )

    def test_all_txt_files(self):
        import user_code
        importlib.reload(user_code)
        files = ["x.txt", "y.txt", "z.txt"]
        f = io.StringIO()
        with redirect_stdout(f):
            user_code.filter_txt_files(files)
        output = normalize_text(f.getvalue())
        for name in files:
            _dynamic_test(
                self,
                normalize_text(name) in output,
                f"All .txt files are printed: {name}",
                f"Expected '{name}' to be printed, got: {output}",
            )
        # Ensure no unexpected output
        lines = [line for line in output.splitlines() if line.strip()]
        _dynamic_test(
            self,
            len(lines) == len(files),
            "Only .txt files are printed",
            f"Expected {len(files)} lines, got: {lines}",
        )

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

Learn how to automate everyday and system-related tasks using Python. This beginner-friendly course alternates between conceptual explanations and hands-on tasks, guiding you through practical automation scenarios and essential system operations.

Explore practical automation scenarios using Python, from simple repetitive tasks to essential system operations. Alternate between conceptual learning and hands-on practice.

Challenge: List Files with Extension

Solution