Refuse Anything That Is Not a File or a Directory, Not Merely What Is Absent

Testing for existence covered a typo and nothing else. A FIFO, a socket,
and a device all exist and are neither a file nor a directory, and
`discover` reads each of them as `.`, so the run still scanned the caller's
directory while the rule set anchored on the argument's parent. The
invariant held for the case I pictured and not for its siblings.
The check now asks what the path is rather than whether it is there, which
covers both.
Two cases: the missing path, and a real FIFO created in the test, skipped
where `os.mkfifo` is unavailable.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: ptr727

scripts/prose_lint.py

@@ -1119,14 +1119,15 @@ def main(argv: list[str] | None = None) -> int:
 # Only a repository declares a model, so two of them refuse and anything else resolves to one anchor.
 # TestScanRootDecidesTheRuleSet carries the cases and the reason each one exists.
 scan_paths=a.pathsor ['.']
-# A path that does not exist is refused rather than absorbed.
-# `discover` reads a non-file, non-directory argument as `.`, so a typo scanned the caller's directory while the rule set anchored on the missing path's parent.
-absent= [pforpinscan_pathsifnotPath(p).exists()]
-ifabsent:
+# Anything that is not a file or a directory is refused rather than absorbed.
+# `discover` reads such an argument as `.`, so it scanned the caller's directory while the rule set anchored on the argument's parent.
+# Tested for what it is rather than for whether it exists, since a FIFO, a socket, and a device all exist and are none of the two.
+unusable= [pforpinscan_pathsifnot (Path(p).is_file() orPath(p).is_dir())]
+ifunusable:
 # Quoted, since a path holding a space or a comma is unreadable in a bare comma-joined list.
-print(f"error: requested path(s) do not exist: {quoted(absent)}. Refusing rather than "
-'falling back to the current directory, which would scan one tree and choose the '
-'rule set from another.', file=sys.stderr)
+print(f"error: requested path(s) are not a file or a directory: {quoted(unusable)}. "
+'Refusing rather than falling back to the current directory, which would scan one '
+'tree and choose the rule set from another.', file=sys.stderr)
 return2
 git_roots= {foundforfoundin (repo_root(Path(p)) forpinscan_paths) iffound}
 iflen(git_roots) >1:

scripts/test_prose_lint.py

@@ -12,6 +12,7 @@
 importcontextlib
 importio
 importjson
+importos
 importre
 importsubprocess
 importsys
@@ -1866,7 +1867,20 @@ def test_a_path_that_does_not_exist_is_refused_rather_than_absorbed(self) -> Non
 withmock.patch.object(prose_lint, 'repo_root', return_value=''):
 self.assertEqual(2, prose_lint.main(
  [str(self.tmp/'no-such-dir'), '--check', 'home-path']))
-self.assertIn('do not exist', self.err.getvalue())
+self.assertIn('not a file or a directory', self.err.getvalue())
+
+@unittest.skipUnless(hasattr(os, 'mkfifo'), 'mkfifo is POSIX only')
+deftest_a_path_that_exists_but_is_neither_a_file_nor_a_directory_is_refused(self) ->None:
+"""A FIFO, a socket, and a device all exist, and `discover` reads each of them as `.`.
+
+ Testing for existence therefore left the hole open on everything that is not a typo.
+ """
+fifo=self.tmp/'a-fifo'
+os.mkfifo(fifo)
+self.assertTrue(fifo.exists())
+withmock.patch.object(prose_lint, 'repo_root', return_value=''):
+self.assertEqual(2, prose_lint.main([str(fifo), '--check', 'home-path']))
+self.assertIn('not a file or a directory', self.err.getvalue())
 
 deftest_a_path_holding_a_space_or_comma_is_quoted_in_the_refusal(self) ->None:
 """Joined bare, one path with a comma in it reads as two paths and the message misleads."""