Issue #8300 (__index__ handling in struct.pack): Remove redundant check

and improve test coverage.  Thanks Meador Inge for the patch.

1 files changed, 27 insertions, 10 deletions

diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index 3e7b259..aeb52f8 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -289,6 +289,25 @@ class StructTest(unittest.TestCase):
                     def __long__(self):
                         return -163L
 
+                # Objects with an '__index__' method should be allowed
+                # to pack as integers.  That is assuming the implemented
+                # '__index__' method returns and 'int' or 'long'.
+                class Indexable(object):
+                    def __init__(self, value):
+                        self._value = value
+
+                    def __index__(self):
+                        return self._value
+
+                # If the '__index__' method raises a type error, then
+                # '__int__' should be used with a deprecation warning.
+                class BadIndex(object):
+                    def __index__(self):
+                        raise TypeError
+
+                    def __int__(self):
+                        return 42
+
                 self.assertRaises((TypeError, struct.error),
                                   struct.pack, self.format,
                                   "a string")
@@ -304,7 +323,7 @@ class StructTest(unittest.TestCase):
                 # an attempt to convert a non-integer (with an
                 # implicit conversion via __int__) should succeed,
                 # with a DeprecationWarning
-                for nonint in NotAnIntNS(), NotAnIntOS():
+                for nonint in NotAnIntNS(), NotAnIntOS(), BadIndex():
                     with check_warnings((".*integer argument expected, got non"
                                          "-integer", DeprecationWarning)) as w:
                         got = struct.pack(self.format, nonint)
@@ -315,15 +334,7 @@ class StructTest(unittest.TestCase):
                     expected = struct.pack(self.format, int(nonint))
                     self.assertEqual(got, expected)
 
-                # Objects with an '__index__' method should be allowed
-                # to pack as integers.
-                class Indexable(object):
-                    def __init__(self, value):
-                        self._value = value
-
-                    def __index__(self):
-                        return self._value
-
+                # Check for legitimate values from '__index__'.
                 for obj in (Indexable(0), Indexable(10), Indexable(17),
                             Indexable(42), Indexable(100), Indexable(127)):
                     try:
@@ -332,6 +343,12 @@ class StructTest(unittest.TestCase):
                         self.fail("integer code pack failed on object "
                                   "with '__index__' method")
 
+                # Check for bogus values from '__index__'.
+                for obj in (Indexable('a'), Indexable(u'b'), Indexable(None),
+                            Indexable({'a': 1}), Indexable([1, 2, 3])):
+                    self.assertRaises((TypeError, struct.error),
+                                      struct.pack, self.format,
+                                      obj)
 
         byteorders = '', '@', '=', '<', '>', '!'
         for code in integer_codes: