gh-78707: deprecate passing >1 argument to `PurePath.[is_]relative_to()` (GH-94469)

This brings `relative_to()` and `is_relative_to()` more in line with other pathlib methods like `rename()` and `symlink_to()`.

Resolves #78707.

1 files changed, 5 insertions, 3 deletions

diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
index 1d01d3c..fa6ea0a 100644
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -654,8 +654,9 @@ class _BasePurePathTest(object):
         self.assertEqual(p.relative_to(P('c'), walk_up=True), P('../a/b'))
         self.assertEqual(p.relative_to('c', walk_up=True), P('../a/b'))
         # With several args.
-        self.assertEqual(p.relative_to('a', 'b'), P())
-        self.assertEqual(p.relative_to('a', 'b', walk_up=True), P())
+        with self.assertWarns(DeprecationWarning):
+            p.relative_to('a', 'b')
+            p.relative_to('a', 'b', walk_up=True)
         # Unrelated paths.
         self.assertRaises(ValueError, p.relative_to, P('c'))
         self.assertRaises(ValueError, p.relative_to, P('a/b/c'))
@@ -706,7 +707,8 @@ class _BasePurePathTest(object):
         self.assertTrue(p.is_relative_to(P('a/b')))
         self.assertTrue(p.is_relative_to('a/b'))
         # With several args.
-        self.assertTrue(p.is_relative_to('a', 'b'))
+        with self.assertWarns(DeprecationWarning):
+            p.is_relative_to('a', 'b')
         # Unrelated paths.
         self.assertFalse(p.is_relative_to(P('c')))
         self.assertFalse(p.is_relative_to(P('a/b/c')))