Issue #15467: Move helpers for __sizeof__ tests into test_support.

Patch by Serhiy Storchaka.

Lib/test/test_struct.py

@@ -3,8 +3,8 @@ import array
 import unittest
 import struct
 import inspect
-from test.test_support import (run_unittest, check_warnings,
-                               check_py3k_warnings, cpython_only)
+from test import test_support as support
+from test.test_support import (check_warnings, check_py3k_warnings)
 
 import sys
 ISBIGENDIAN = sys.byteorder == "big"
@@ -33,33 +33,6 @@ def bigendian_to_native(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 check_float_coerce(self, format, number):
         # SF bug 1530559. struct.pack raises TypeError where it used
         # to convert.
@@ -572,7 +545,14 @@ class StructTest(unittest.TestCase):
         hugecount2 = '{}b{}H'.format(sys.maxsize//2, sys.maxsize//2)
         self.assertRaises(struct.error, struct.calcsize, hugecount2)
 
-    @cpython_only
+    def check_sizeof(self, format_str, number_of_codes):
+        # The size of 'PyStructObject'
+        totalsize = support.calcobjsize('5P')
+        # The size taken up by the 'formatcode' dynamic array
+        totalsize += struct.calcsize('3P') * (number_of_codes + 1)
+        support.check_sizeof(self, struct.Struct(format_str), totalsize)
+
+    @support.cpython_only
     def test__sizeof__(self):
         for code in integer_codes:
             self.check_sizeof(code, 1)
@@ -587,7 +567,7 @@ class StructTest(unittest.TestCase):
         self.check_sizeof('0c', 0)
 
 def test_main():
-    run_unittest(StructTest)
+    support.run_unittest(StructTest)
 
 if __name__ == '__main__':
     test_main()

Lib/test/test_support.py

@@ -18,6 +18,8 @@ import importlib
 import UserDict
 import re
 import time
+import struct
+import _testcapi
 try:
     import thread
 except ImportError:
@@ -861,6 +863,32 @@ def gc_collect():
     gc.collect()
 
 
+_header = '2P'
+if hasattr(sys, "gettotalrefcount"):
+    _header = '2P' + _header
+_vheader = _header + 'P'
+
+def calcobjsize(fmt):
+    return struct.calcsize(_header + fmt + '0P')
+
+def calcvobjsize(fmt):
+    return struct.calcsize(_vheader + fmt + '0P')
+
+
+_TPFLAGS_HAVE_GC = 1<<14
+_TPFLAGS_HEAPTYPE = 1<<9
+
+def check_sizeof(test, o, size):
+    result = sys.getsizeof(o)
+    # add GC header size
+    if ((type(o) == type) and (o.__flags__ & _TPFLAGS_HEAPTYPE) or\
+        ((type(o) != type) and (type(o).__flags__ & _TPFLAGS_HAVE_GC))):
+        size += _testcapi.SIZEOF_PYGC_HEAD
+    msg = 'wrong size for %s: got %d, expected %d' \
+            % (type(o), result, size)
+    test.assertEqual(result, size, msg)
+
+
 #=======================================================================
 # Decorator for running a function in a different locale, correctly resetting
 # it afterwards.

Misc/NEWS

@@ -887,6 +887,9 @@ Tools/Demos
 Tests
 -----
 
+- Issue #15467: Move helpers for __sizeof__ tests into test_support.
+  Patch by Serhiy Storchaka.
+
 - Issue #11689: Fix a variable scoping error in an sqlite3 test.
   Initial patch by Torsten Landschoff.