Issue #15402: Simplify Struct.__sizeof__ and make tests more precise.
diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index be32d88..b77982e 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -3,7 +3,7 @@
import struct
import sys
-from test.support import run_unittest
+from test.support import run_unittest, cpython_only
ISBIGENDIAN = sys.byteorder == "big"
IS32BIT = sys.maxsize == 0x7fffffff
@@ -30,6 +30,33 @@
return string_reverse(value)
class StructTest(unittest.TestCase):
+ def setUp(self):
+ # due to missing size_t information from struct, it is assumed that
+ # sizeof(Py_ssize_t) = sizeof(void*)
+ self.header = 'PP'
+ if hasattr(sys, "gettotalrefcount"):
+ self.header += '2P'
+
+ def check_sizeof(self, format_str, number_of_codes):
+ def size(fmt):
+ """Wrapper around struct.calcsize which enforces the alignment
+ of the end of a structure to the alignment requirement of pointer.
+
+ Note: This wrapper should only be used if a pointer member is
+ included and no member with a size larger than a pointer exists.
+ """
+ return struct.calcsize(fmt + '0P')
+
+ struct_obj = struct.Struct(format_str)
+ # The size of 'PyStructObject'
+ totalsize = size(self.header + '5P')
+ # The size taken up by the 'formatcode' dynamic array
+ totalsize += size('3P') * (number_of_codes + 1)
+ result = sys.getsizeof(struct_obj)
+ msg = 'wrong size for %s: got %d, expected %d' \
+ % (type(struct_obj), result, totalsize)
+ self.assertEqual(result, totalsize, msg)
+
def test_isbigendian(self):
self.assertEqual((struct.pack('=i', 1)[0] == 0), ISBIGENDIAN)
@@ -556,15 +583,19 @@
s = struct.Struct('i')
s.__init__('ii')
- def test_sizeof(self):
- self.assertGreater(sys.getsizeof(struct.Struct('BHILfdspP')),
- sys.getsizeof(struct.Struct('B')))
- self.assertGreater(sys.getsizeof(struct.Struct('123B')),
- sys.getsizeof(struct.Struct('B')))
- self.assertGreater(sys.getsizeof(struct.Struct('B' * 1234)),
- sys.getsizeof(struct.Struct('123B')))
- self.assertGreater(sys.getsizeof(struct.Struct('1234B')),
- sys.getsizeof(struct.Struct('123B')))
+ @cpython_only
+ def test__sizeof__(self):
+ for code in integer_codes:
+ self.check_sizeof(code, 1)
+ self.check_sizeof('BHILfdspP', 9)
+ self.check_sizeof('B' * 1234, 1234)
+ self.check_sizeof('fd', 2)
+ self.check_sizeof('xxxxxxxxxxxxxx', 0)
+ self.check_sizeof('100H', 100)
+ self.check_sizeof('187s', 1)
+ self.check_sizeof('20p', 1)
+ self.check_sizeof('0s', 1)
+ self.check_sizeof('0c', 0)
def test_main():
run_unittest(StructTest)