test_fuzz.py

#!/usr/bin/env python
"""Test that autoflake performs correctly on arbitrary Python files.

This checks that autoflake never introduces incorrect syntax. This is
done by doing a syntax check after the autoflake run. The number of
Pyflakes warnings is also confirmed to always improve.
"""
from __future__ import annotations

import argparse
import os
import shlex
import subprocess
import sys
from typing import Sequence

import autoflake


ROOT_PATH = os.path.abspath(os.path.dirname(__file__))
AUTOFLAKE_BIN = "'{}' '{}'".format(
    sys.executable,
    os.path.join(ROOT_PATH, "autoflake.py"),
)

if sys.stdout.isatty():
    YELLOW = "\x1b[33m"
    END = "\x1b[0m"
else:
    YELLOW = ""
    END = ""


def colored(text: str, color: str) -> str:
    """Return color coded text."""
    return color + text + END


def pyflakes_count(filename: str) -> int:
    """Return pyflakes error count."""
    with autoflake.open_with_encoding(
        filename,
        encoding=autoflake.detect_encoding(filename),
    ) as f:
        return len(list(autoflake.check(f.read())))


def readlines(filename: str) -> Sequence[str]:
    """Return contents of file as a list of lines."""
    with autoflake.open_with_encoding(
        filename,
        encoding=autoflake.detect_encoding(filename),
    ) as f:
        return f.readlines()


def diff(before: str, after: str) -> str:
    """Return diff of two files."""
    import difflib

    return "".join(
        difflib.unified_diff(
            readlines(before),
            readlines(after),
            before,
            after,
        ),
    )


def run(
    filename: str,
    command: str,
    verbose: bool = False,
    options: list[str] | None = None,
) -> bool:
    """Run autoflake on file at filename.

    Return True on success.
    """
    if not options:
        options = []

    import test_autoflake

    with test_autoflake.temporary_directory() as temp_directory:
        temp_filename = os.path.join(
            temp_directory,
            os.path.basename(filename),
        )
        import shutil

        shutil.copyfile(filename, temp_filename)

        if 0 != subprocess.call(
            shlex.split(command) + ["--in-place", temp_filename] + options,
        ):
            sys.stderr.write("autoflake crashed on " + filename + "\n")
            return False

        try:
            file_diff = diff(filename, temp_filename)
            if verbose:
                sys.stderr.write(file_diff)

            if check_syntax(filename):
                try:
                    check_syntax(temp_filename, raise_error=True)
                except (
                    SyntaxError,
                    TypeError,
                    UnicodeDecodeError,
                    ValueError,
                ) as exception:
                    sys.stderr.write(
                        "autoflake broke " + filename + "\n" + str(exception) + "\n",
                    )
                    return False

            before_count = pyflakes_count(filename)
            after_count = pyflakes_count(temp_filename)

            if verbose:
                print("(before, after):", (before_count, after_count))

            if file_diff and after_count > before_count:
                sys.stderr.write("autoflake made " + filename + " worse\n")
                return False
        except OSError as exception:
            sys.stderr.write(str(exception) + "\n")

    return True


def check_syntax(filename: str, raise_error: bool = False) -> bool:
    """Return True if syntax is okay."""
    with autoflake.open_with_encoding(
        filename,
        encoding=autoflake.detect_encoding(filename),
    ) as input_file:
        try:
            compile(input_file.read(), "<string>", "exec", dont_inherit=True)
            return True
        except (SyntaxError, TypeError, UnicodeDecodeError, ValueError):
            if raise_error:
                raise
            else:
                return False


def process_args() -> argparse.Namespace:
    """Return processed arguments (options and positional arguments)."""
    parser = argparse.ArgumentParser()

    parser.add_argument(
        "--command",
        default=AUTOFLAKE_BIN,
        help="autoflake command (default: %(default)s)",
    )

    parser.add_argument(
        "--expand-star-imports",
        action="store_true",
        help="expand wildcard star imports with undefined " "names",
    )

    parser.add_argument(
        "--imports",
        help='pass to the autoflake "--imports" option',
    )

    parser.add_argument(
        "--remove-all-unused-imports",
        action="store_true",
        help='pass "--remove-all-unused-imports" option to ' "autoflake",
    )

    parser.add_argument(
        "--remove-duplicate-keys",
        action="store_true",
        help='pass "--remove-duplicate-keys" option to ' "autoflake",
    )

    parser.add_argument(
        "--remove-unused-variables",
        action="store_true",
        help='pass "--remove-unused-variables" option to ' "autoflake",
    )

    parser.add_argument(
        "-v",
        "--verbose",
        action="store_true",
        help="print verbose messages",
    )

    parser.add_argument("files", nargs="*", help="files to test against")

    return parser.parse_args()


def check(args: argparse.Namespace) -> bool:
    """Run recursively run autoflake on directory of files.

    Return False if the fix results in broken syntax.
    """
    if args.files:
        dir_paths = args.files
    else:
        dir_paths = [path for path in sys.path if os.path.isdir(path)]

    options = []
    if args.expand_star_imports:
        options.append("--expand-star-imports")

    if args.imports:
        options.append("--imports=" + args.imports)

    if args.remove_all_unused_imports:
        options.append("--remove-all-unused-imports")

    if args.remove_duplicate_keys:
        options.append("--remove-duplicate-keys")

    if args.remove_unused_variables:
        options.append("--remove-unused-variables")

    filenames = dir_paths
    completed_filenames = set()

    while filenames:
        try:
            name = os.path.realpath(filenames.pop(0))
            if not os.path.exists(name):
                # Invalid symlink.
                continue

            if name in completed_filenames:
                sys.stderr.write(
                    colored(
                        "--->  Skipping previously tested " + name + "\n",
                        YELLOW,
                    ),
                )
                continue
            else:
                completed_filenames.update(name)

            if os.path.isdir(name):
                for root, directories, children in os.walk(name):
                    filenames += [
                        os.path.join(root, f)
                        for f in children
                        if f.endswith(".py") and not f.startswith(".")
                    ]

                    directories[:] = [d for d in directories if not d.startswith(".")]
            else:
                verbose_message = "--->  Testing with " + name
                sys.stderr.write(colored(verbose_message + "\n", YELLOW))

                if not run(
                    os.path.join(name),
                    command=args.command,
                    verbose=args.verbose,
                    options=options,
                ):
                    return False
        except (UnicodeDecodeError, UnicodeEncodeError) as exception:
            # Ignore annoying codec problems on Python 2.
            print(exception, file=sys.stderr)
            continue

    return True


def main() -> int:
    """Run main."""
    return 0 if check(process_args()) else 1


if __name__ == "__main__":
    try:
        sys.exit(main())
    except KeyboardInterrupt:
        sys.exit(1)