From 62f9588663ebfea1735e9d142ef527395a6c2b95 Mon Sep 17 00:00:00 2001
From: Inada Naoki <songofacandy@gmail.com>
Date: Mon, 1 Apr 2019 17:56:11 +0900
Subject: bpo-36026: make descr error message consistent (GH-11930)

set.add(0) and set.add.__get__(0) now raise TypeError
with same error message.
---
 Lib/test/test_descr.py | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

(limited to 'Lib/test/test_descr.py')

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 09eef8c56f..e37a98417f 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -1614,10 +1614,14 @@ order (MRO) for bases """
 
         with self.assertRaises(TypeError) as cm:
             spam_cm(list)
-        self.assertEqual(
-            str(cm.exception),
+        expected_errmsg = (
             "descriptor 'classmeth' requires a subtype of 'xxsubtype.spamlist' "
             "but received 'list'")
+        self.assertEqual(str(cm.exception), expected_errmsg)
+
+        with self.assertRaises(TypeError) as cm:
+            spam_cm.__get__(None, list)
+        self.assertEqual(str(cm.exception), expected_errmsg)
 
     def test_staticmethods(self):
         # Testing static methods...
@@ -1952,6 +1956,29 @@ order (MRO) for bases """
         self.assertEqual(E().foo.__func__, C.foo) # i.e., unbound
         self.assertTrue(repr(C.foo.__get__(C(1))).startswith("<bound method "))
 
+    @support.impl_detail("testing error message from implementation")
+    def test_methods_in_c(self):
+        # This test checks error messages in builtin method descriptor.
+        # It is allowed that other Python implementations use
+        # different error messages.
+        set_add = set.add
+
+        expected_errmsg = "descriptor 'add' of 'set' object needs an argument"
+
+        with self.assertRaises(TypeError) as cm:
+            set_add()
+        self.assertEqual(cm.exception.args[0], expected_errmsg)
+
+        expected_errmsg = "descriptor 'add' for 'set' objects doesn't apply to a 'int' object"
+
+        with self.assertRaises(TypeError) as cm:
+            set_add(0)
+        self.assertEqual(cm.exception.args[0], expected_errmsg)
+
+        with self.assertRaises(TypeError) as cm:
+            set_add.__get__(0)
+        self.assertEqual(cm.exception.args[0], expected_errmsg)
+
     def test_special_method_lookup(self):
         # The lookup of special methods bypasses __getattr__ and
         # __getattribute__, but they still can be descriptors.
-- 
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