From f9e63868db9b7ed3399f28fd1eb5bcd02a4f5e73 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Luis=20P=C3=A9rez?= <luis.i.perez.0@gmail.com>
Date: Sun, 6 Oct 2024 00:57:18 -0400
Subject: [PATCH] Disallow --unique alongside --ignore-cases in
 file-contents-sorter

Closes #794: using these flags at the same time results in undefined
behavior - the final ordering is not guaranteed as --unique breaks
sorting due to passing the contents through a set.

NOTE: I added a newline before and after the mutex group to be
consistent with other usages of mutex groups (e.g.,
check_builtin_literals.py) in this repo.
---
 pre_commit_hooks/file_contents_sorter.py |  7 ++++--
 tests/file_contents_sorter_test.py       | 32 +++++++++++++++---------
 2 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/pre_commit_hooks/file_contents_sorter.py b/pre_commit_hooks/file_contents_sorter.py
index 02bdbccf..0e2d665c 100644
--- a/pre_commit_hooks/file_contents_sorter.py
+++ b/pre_commit_hooks/file_contents_sorter.py
@@ -54,18 +54,21 @@ def sort_file_contents(
 def main(argv: Sequence[str] | None = None) -> int:
     parser = argparse.ArgumentParser()
     parser.add_argument('filenames', nargs='+', help='Files to sort')
-    parser.add_argument(
+
+    mutex = parser.add_mutually_exclusive_group(required=False)
+    mutex.add_argument(
         '--ignore-case',
         action='store_const',
         const=bytes.lower,
         default=None,
         help='fold lower case to upper case characters',
     )
-    parser.add_argument(
+    mutex.add_argument(
         '--unique',
         action='store_true',
         help='ensure each line is unique',
     )
+
     args = parser.parse_args(argv)
 
     retv = PASS
diff --git a/tests/file_contents_sorter_test.py b/tests/file_contents_sorter_test.py
index 49b3b793..dfaed7b6 100644
--- a/tests/file_contents_sorter_test.py
+++ b/tests/file_contents_sorter_test.py
@@ -67,18 +67,6 @@
             FAIL,
             b'Fie\nFoe\nfee\nfum\n',
         ),
-        (
-            b'fee\nFie\nFoe\nfum\n',
-            ['--unique', '--ignore-case'],
-            PASS,
-            b'fee\nFie\nFoe\nfum\n',
-        ),
-        (
-            b'fee\nfee\nFie\nFoe\nfum\n',
-            ['--unique', '--ignore-case'],
-            FAIL,
-            b'fee\nFie\nFoe\nfum\n',
-        ),
     ),
 )
 def test_integration(input_s, argv, expected_retval, output, tmpdir):
@@ -89,3 +77,23 @@ def test_integration(input_s, argv, expected_retval, output, tmpdir):
 
     assert path.read_binary() == output
     assert output_retval == expected_retval
+
+@pytest.mark.parametrize(
+    ("input_s", "argv"),
+    (
+        (
+            b"fee\nFie\nFoe\nfum\n",
+            ["--unique", "--ignore-case"],
+        ),
+        (
+            b"fee\nfee\nFie\nFoe\nfum\n",
+            ["--unique", "--ignore-case"],
+        ),
+    ),
+)
+def test_integration_invalid_args(input_s, argv, tmpdir):
+    path = tmpdir.join("file.txt")
+    path.write_binary(input_s)
+
+    with pytest.raises(SystemExit):
+        main([str(path)] + argv)