Issue 7994: Make object.__format__() raise a PendingDeprecationWarning

if the format string is not empty. Manually merge r79596 and r84772
from 2.x.

Also, apparently test_format() from test_builtin never made it into
3.x. I've added it as well. It tests the basic format()
infrastructure.

1 files changed, 7 insertions, 4 deletions

diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 0ada5cca1a..f6c38dd1ea 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -609,13 +609,16 @@ class UnicodeTest(string_tests.CommonTest,
         self.assertEqual('{0}'.format({}), '{}')
         self.assertEqual('{0}'.format([]), '[]')
         self.assertEqual('{0}'.format([1]), '[1]')
-        self.assertEqual('{0}'.format(E('data')), 'E(data)')
-        self.assertEqual('{0:^10}'.format(E('data')), ' E(data)  ')
-        self.assertEqual('{0:^10s}'.format(E('data')), ' E(data)  ')
+
         self.assertEqual('{0:d}'.format(G('data')), 'G(data)')
-        self.assertEqual('{0:>15s}'.format(G('data')), ' string is data')
         self.assertEqual('{0!s}'.format(G('data')), 'string is data')
 
+        msg = 'object.__format__ with a non-empty format string is deprecated'
+        with support.check_warnings((msg, PendingDeprecationWarning)):
+            self.assertEqual('{0:^10}'.format(E('data')), ' E(data)  ')
+            self.assertEqual('{0:^10s}'.format(E('data')), ' E(data)  ')
+            self.assertEqual('{0:>15s}'.format(G('data')), ' string is data')
+
         self.assertEqual("{0:date: %Y-%m-%d}".format(I(year=2007,
                                                        month=8,
                                                        day=27)),