gh-87106: Fix inspect.signature.bind() handling of positional-only arguments with **kwargs (GH-103404)

1 files changed, 20 insertions, 5 deletions

diff --git a/Lib/test/test_inspect/test_inspect.py b/Lib/test/test_inspect/test_inspect.py
index 8bd1303..011d42f 100644
--- a/Lib/test/test_inspect/test_inspect.py
+++ b/Lib/test/test_inspect/test_inspect.py
@@ -5089,15 +5089,30 @@ class TestSignatureBind(unittest.TestCase):
         self.assertEqual(self.call(test, 1, 2, foo=4, bar=5),
                          (1, 2, 3, 4, 5, {}))
 
-        with self.assertRaisesRegex(TypeError, "but was passed as a keyword"):
-            self.call(test, 1, 2, foo=4, bar=5, c_po=10)
+        self.assertEqual(self.call(test, 1, 2, foo=4, bar=5, c_po=10),
+                         (1, 2, 3, 4, 5, {'c_po': 10}))
 
-        with self.assertRaisesRegex(TypeError, "parameter is positional only"):
-            self.call(test, 1, 2, c_po=4)
+        self.assertEqual(self.call(test, 1, 2, 30, c_po=31, foo=4, bar=5),
+                         (1, 2, 30, 4, 5, {'c_po': 31}))
 
-        with self.assertRaisesRegex(TypeError, "parameter is positional only"):
+        self.assertEqual(self.call(test, 1, 2, 30, foo=4, bar=5, c_po=31),
+                         (1, 2, 30, 4, 5, {'c_po': 31}))
+
+        self.assertEqual(self.call(test, 1, 2, c_po=4),
+                         (1, 2, 3, 42, 50, {'c_po': 4}))
+
+        with self.assertRaisesRegex(TypeError, "missing 2 required positional arguments"):
             self.call(test, a_po=1, b_po=2)
 
+        def without_var_kwargs(c_po=3, d_po=4, /):
+            return c_po, d_po
+
+        with self.assertRaisesRegex(
+            TypeError,
+            "positional-only arguments passed as keyword arguments: 'c_po, d_po'",
+        ):
+            self.call(without_var_kwargs, c_po=33, d_po=44)
+
     def test_signature_bind_with_self_arg(self):
         # Issue #17071: one of the parameters is named "self
         def test(a, self, b):