Add edge case: patterns that end with an escaped space

pathspec/patterns/gitwildmatch.py

@@ -68,7 +68,14 @@ def pattern_to_regex(
 			raise TypeError(f"pattern:{pattern!r} is not a unicode or byte string.")
 
 		original_pattern = pattern
-		pattern = pattern.strip()
+
+		if pattern.endswith('\\ '):
+			# EDGE CASE: Spaces can be escaped with backslash.
+			# If a pattern that ends with backslash followed by a space,
+			# only strip from left.
+			pattern = pattern.lstrip()
+		else:
+			pattern = pattern.strip()
 
 		if pattern.startswith('#'):
 			# A pattern starting with a hash ('#') serves as a comment

tests/test_pathspec.py

@@ -15,6 +15,7 @@
 	PathSpec)
 from pathspec.util import (
 	iter_tree_entries)
+from pathspec.patterns.gitwildmatch import GitWildMatchPatternError
 from tests.util import (
 	make_dirs,
 	make_files,
@@ -119,6 +120,32 @@ def test_01_current_dir_paths(self):
 			'./src/test2/c/c.txt',
 		})
 
+	def test_01_empty_path(self):
+		"""
+		Tests that patterns that end with an escaped space will be treated properly.
+		"""
+		spec = PathSpec.from_lines('gitwildmatch', [
+			'\\ ',
+			'abc\\ '
+		])
+		test_files = [
+			' ',
+			'  ',
+			'abc ',
+			'somefile',
+		]
+		results = list(filter(spec.match_file, test_files))
+		self.assertEqual(results, [
+			' ',
+			'abc '
+		])
+
+		# An escape with double spaces is invalid.
+		# Disallow it. Better to be safe than sorry.
+		self.assertRaises(GitWildMatchPatternError, lambda: PathSpec.from_lines('gitwildmatch', [
+			'\\  '
+		]))
+
 	def test_01_match_files(self):
 		"""
 		Tests that matching files one at a time yields the same results as