PEP 465: a dedicated infix operator for matrix multiplication (closes #21176)
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 408f12c..ba7f2c4 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -150,6 +150,23 @@
         self.assertEqual(_testcapi.docstring_with_signature_and_extra_newlines.__text_signature__,
             "($module, /, parameter)")
 
+    def test_c_type_with_matrix_multiplication(self):
+        M = _testcapi.matmulType
+        m1 = M()
+        m2 = M()
+        self.assertEqual(m1 @ m2, ("matmul", m1, m2))
+        self.assertEqual(m1 @ 42, ("matmul", m1, 42))
+        self.assertEqual(42 @ m1, ("matmul", 42, m1))
+        o = m1
+        o @= m2
+        self.assertEqual(o, ("imatmul", m1, m2))
+        o = m1
+        o @= 42
+        self.assertEqual(o, ("imatmul", m1, 42))
+        o = 42
+        o @= m1
+        self.assertEqual(o, ("matmul", 42, m1))
+
 
 @unittest.skipUnless(threading, 'Threading required for this test.')
 class TestPendingCalls(unittest.TestCase):