gh-104803: Implement ntpath.isdevdrive for checking whether a path is on a Windows Dev Drive (GH-104805)

2 files changed, 36 insertions, 0 deletions

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 0f3674f..dadcdc0 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -867,3 +867,19 @@ try:
 except ImportError:
     # Use genericpath.* as imported above
     pass
+
+
+try:
+    from nt import _path_isdevdrive
+except ImportError:
+    def isdevdrive(path):
+        """Determines whether the specified path is on a Windows Dev Drive."""
+        # Never a Dev Drive
+        return False
+else:
+    def isdevdrive(path):
+        """Determines whether the specified path is on a Windows Dev Drive."""
+        try:
+            return _path_isdevdrive(abspath(path))
+        except OSError:
+            return False
diff --git a/Lib/test/test_ntpath.py b/Lib/test/test_ntpath.py
index 0e57c16..538d758 100644
--- a/Lib/test/test_ntpath.py
+++ b/Lib/test/test_ntpath.py
@@ -992,6 +992,26 @@ class TestNtpath(NtpathTestCase):
         self.assertTrue(os.path.exists is nt._path_exists)
         self.assertFalse(inspect.isfunction(os.path.exists))
 
+    @unittest.skipIf(os.name != 'nt', "Dev Drives only exist on Win32")
+    def test_isdevdrive(self):
+        # Result may be True or False, but shouldn't raise
+        self.assertIn(ntpath.isdevdrive(os_helper.TESTFN), (True, False))
+        # ntpath.isdevdrive can handle relative paths
+        self.assertIn(ntpath.isdevdrive("."), (True, False))
+        self.assertIn(ntpath.isdevdrive(b"."), (True, False))
+        # Volume syntax is supported
+        self.assertIn(ntpath.isdevdrive(os.listvolumes()[0]), (True, False))
+        # Invalid volume returns False from os.path method
+        self.assertFalse(ntpath.isdevdrive(r"\\?\Volume{00000000-0000-0000-0000-000000000000}\\"))
+        # Invalid volume raises from underlying helper
+        with self.assertRaises(OSError):
+            nt._path_isdevdrive(r"\\?\Volume{00000000-0000-0000-0000-000000000000}\\")
+
+    @unittest.skipIf(os.name == 'nt', "isdevdrive fallback only used off Win32")
+    def test_isdevdrive_fallback(self):
+        # Fallback always returns False
+        self.assertFalse(ntpath.isdevdrive(os_helper.TESTFN))
+
 
 class NtCommonTest(test_genericpath.CommonTest, unittest.TestCase):
     pathmodule = ntpath