lib/python2.7/ctypes/test/test_values.py

"""
A testcase which accesses *values* in a dll.
"""

import unittest
from ctypes import *

import _ctypes_test

class ValuesTestCase(unittest.TestCase):

    def test_an_integer(self):
        ctdll = CDLL(_ctypes_test.__file__)
        an_integer = c_int.in_dll(ctdll, "an_integer")
        x = an_integer.value
        self.assertEqual(x, ctdll.get_an_integer())
        an_integer.value *= 2
        self.assertEqual(x*2, ctdll.get_an_integer())

    def test_undefined(self):
        ctdll = CDLL(_ctypes_test.__file__)
        self.assertRaises(ValueError, c_int.in_dll, ctdll, "Undefined_Symbol")

    class Win_ValuesTestCase(unittest.TestCase):
        """This test only works when python itself is a dll/shared library"""

        def test_optimizeflag(self):
            # This test accesses the Py_OptimizeFlag intger, which is
            # exported by the Python dll.

            # It's value is set depending on the -O and -OO flags:
            # if not given, it is 0 and __debug__ is 1.
            # If -O is given, the flag is 1, for -OO it is 2.
            # docstrings are also removed in the latter case.
            opt = c_int.in_dll(pydll, "Py_OptimizeFlag").value
            if __debug__:
                self.assertEqual(opt, 0)
            elif ValuesTestCase.__doc__ is not None:
                self.assertEqual(opt, 1)
            else:
                self.assertEqual(opt, 2)

        def test_frozentable(self):
            # Python exports a PyImport_FrozenModules symbol. This is a
            # pointer to an array of struct _frozen entries.  The end of the
            # array is marked by an entry containing a NULL name and zero
            # size.

            # In standard Python, this table contains a __hello__
            # module, and a __phello__ package containing a spam
            # module.
            class struct_frozen(Structure):
                _fields_ = [("name", c_char_p),
                            ("code", POINTER(c_ubyte)),
                            ("size", c_int)]
            FrozenTable = POINTER(struct_frozen)

            ft = FrozenTable.in_dll(pydll, "PyImport_FrozenModules")
            # ft is a pointer to the struct_frozen entries:
            items = []
            for entry in ft:
                # This is dangerous. We *can* iterate over a pointer, but
                # the loop will not terminate (maybe with an access
                # violation;-) because the pointer instance has no size.
                if entry.name is None:
                    break
                items.append((entry.name, entry.size))
            import sys
            if sys.version_info[:2] >= (2, 3):
                expected = [("__hello__", 104), ("__phello__", -104), ("__phello__.spam", 104)]
            else:
                expected = [("__hello__", 100), ("__phello__", -100), ("__phello__.spam", 100)]
            self.assertEqual(items, expected)

            from ctypes import _pointer_type_cache
            del _pointer_type_cache[struct_frozen]

        def test_undefined(self):
            self.assertRaises(ValueError, c_int.in_dll, pydll, "Undefined_Symbol")

if __name__ == '__main__':
    unittest.main()