patterns: add path existence validation for RootPath, improve test coverage

Author: mr-raj12

src/borg/patterns.py

@@ -4,6 +4,7 @@
 import sys
 import unicodedata
 from collections import namedtuple
+import os
 from enum import Enum
 
 from .helpers import clean_lines, shellpattern
@@ -376,8 +377,18 @@ def parse_inclexcl_command(cmd_line_str, fallback=ShellPattern):
         raise ArgumentTypeError("A pattern/command must have a value part.")
 
     if cmd is IECommand.RootPath:
-        if not remainder_str.startswith("/"):
-            logger.warning("Root path %r does not look like an absolute path", remainder_str)
+        # Check if path is absolute
+        is_absolute = remainder_str.startswith("/")
+        # Check if path exists
+        path_exists = os.path.exists(remainder_str)
+        
+        # Warn about relative paths
+        if not is_absolute:
+            logger.warning("Root path %r is relative, recommended to use absolute path", remainder_str)
+        # Warn about non-existent paths
+        if not path_exists:
+            logger.warning("Root path %r does not exist", remainder_str)
+        
         val = remainder_str
     elif cmd is IECommand.PatternStyle:
         # then remainder_str is something like 're' or 'sh'

src/borg/testsuite/patterns_test.py

@@ -632,16 +632,44 @@ def test_command_recurses_dir():
 
 
 def test_root_path_validation(caplog):
+    import tempfile
+    import os as test_os
+    
     caplog.set_level(logging.WARNING, logger="borg.patterns")
 
-    # absolute path should not warn
-    parse_inclexcl_command("R /absolute/path")
-    assert "does not look like an absolute path" not in caplog.text
+    # Test 1: Unix-style absolute path that doesn't exist
+    # On Unix systems, /absolute/paths don't trigger "relative" warning
+    # On Windows, such paths may not exist but still validate correctly
+    caplog.clear()
+    parse_inclexcl_command("R /absolute/unix/path")
+    # Should not have "relative" warning (starts with /)
+    assert "relative" not in caplog.text
+
+    # Test 2: absolute path that doesn't exist should warn about existence
+    caplog.clear()
+    parse_inclexcl_command("R /nonexistent/absolute/path/12345")
+    assert "does not exist" in caplog.text
 
-    # relative path should warn
+    # Test 3: relative path that exists should warn about relative
+    caplog.clear()
+    with tempfile.TemporaryDirectory() as tmpdir:
+        # Create temp subdir to be relative
+        old_cwd = test_os.getcwd()
+        try:
+            test_os.chdir(tmpdir)
+            # Create a subdir
+            test_os.makedirs("test_root_dir", exist_ok=True)
+            parse_inclexcl_command("R test_root_dir")
+            assert "relative" in caplog.text
+            assert "does not exist" not in caplog.text
+        finally:
+            test_os.chdir(old_cwd)
+
+    # Test 4: relative path that doesn't exist should warn about both
     caplog.clear()
-    parse_inclexcl_command("R relative/path")
-    assert "does not look like an absolute path" in caplog.text
+    parse_inclexcl_command("R relative/nonexistent/path")
+    assert "relative" in caplog.text
+    assert "does not exist" in caplog.text
 
 
 @pytest.mark.parametrize(