[3.13] gh-128613: Increase typing.Concatenate coverage (GH-128614) (#128623)

miss-islington · sobolevn · web-flow · commit 77b411bd90b1 · 2025-01-08T12:26:01.000Z
Co-authored-by: sobolevn &lt;mail@sobolevn.me&gt;
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
@@ -9998,6 +9998,18 @@ def test_valid_uses(self):
         self.assertEqual(C4.__args__, (Concatenate[int, T, P], T))
         self.assertEqual(C4.__parameters__, (T, P))
 
+    def test_invalid_uses(self):
+        with self.assertRaisesRegex(TypeError, 'Concatenate of no types'):
+            Concatenate[()]
+        with self.assertRaisesRegex(
+            TypeError,
+            (
+                'The last parameter to Concatenate should be a '
+                'ParamSpec variable or ellipsis'
+            ),
+        ):
+            Concatenate[int]
+
     def test_var_substitution(self):
         T = TypeVar('T')
         P = ParamSpec('P')
