build/testing/verify_files_match.py

#!/usr/bin/env fuchsia-vendored-python
# Copyright 2021 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import argparse
import filecmp
import sys
import subprocess

# Verifies that two files have matching contents.


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--result-file", help="Path to the victory file", required=True
    )
    parser.add_argument(
        "--diff-on-failure",
        help="Run diff on the files if they differ",
        action="store_true",
    )
    parser.add_argument(
        "--custom-error-message",
        help="Error to print if the files differ",
        default=None,
    )
    parser.add_argument("first")
    parser.add_argument("second")
    args = parser.parse_args()

    if not filecmp.cmp(args.first, args.second):
        # Flush is used to make sure that the print statement occurs before the
        # output of diff.
        print(
            f"Error: file contents differ:\n  {args.first}\n  {args.second}",
            flush=True,
        )
        if args.custom_error_message:
            print(args.custom_error_message, flush=True)
        if args.diff_on_failure:
            subprocess.call(
                ["diff", "-u", args.first, args.second], stderr=sys.stdout
            )
        return 1

    with open(args.result_file, "w") as result_file:
        result_file.write("Match!\n")

    return 0


if __name__ == "__main__":
    sys.exit(main())