In this presentation, I take a brisk walk through a small problem in automated browser testing, take a quick right at Windows, and dash through implementing a new Python module replacing winreg. http://pypi.python.org/pypi/cygwinreg

1. Tilting at Windmills
with
ctypes and cygwinreg
Simon Law
simon@akoha.com

2. def introduction():

4. social reality game

5. def problem():

6. website

8. testing

12. click
wait
look

13. click
wait
look

14. click
wait
look

15. slow

16. laborious

17. boring

18. automated testing

19. def test_browser():

20. © Andy Heatwole
Creative Commons Attribution-NonCommercial-NoDerivs 2.5.
http://blog.bluehourphoto.com/?showimage=224

21. getwindmill.com

26. one script

27. all browsers

28. from windmill.authoring import *
def setup_module(module):
client = WindmillTestClient(__name__)
client.click(id=u'home')
client.waits.forPageLoad(timeout=u'60000')
client.asserts.assertNode(id='LoginPage')

29. from windmill.authoring import *
def setup_module(module):
client = WindmillTestClient(__name__)
client.click(id=u'home')
client.waits.forPageLoad(timeout=u'60000')
client.asserts.assertNode(id='LoginPage')

30. from windmill.authoring import *
def setup_module(module):
client = WindmillTestClient(__name__)
client.click(id=u'home')
client.waits.forPageLoad(timeout=u'60000')
client.asserts.assertNode(id='LoginPage')

31. from windmill.authoring import *
def setup_module(module):
client = WindmillTestClient(__name__)
client.click(id=u'home')
client.waits.forPageLoad(timeout=u'60000')
client.asserts.assertNode(id='LoginPage')

32. semi-automated testing

33. def continuous_integration():

34. test automatically

35. buildbot.net

36. ~/akoha$ make check

37. C:>make check
'make' is not recognized as an
internal or external command,
operable program or batch file.

39. cygwin.com

40. ~/akoha$ make check

41. Traceback (most recent call last):
...
ImportError: No module named _winreg

42. def windows_registry():

43. proxy settings

44. import _winreg

45. import winreg

46. 32.3. winreg
Windows registry access
Platforms: Windows

47. 32.3. winreg
Windows registry access
Platforms: Windows

48. 3 choices

49. 1

50. give up

51. 2

52. recompile Python

53. 3

54. cygwinreg

55. like hurting myself

56. def call_system_libraries():

57. import ctypes

58. foreign function interface

59. call functions

60. shared libraries

61. libiberty.so

62. libgcc.dynlib

63. advapi32.dll

64. >>> from ctypes import cdll

65. >>> cdll.advapi32
<CDLL 'advapi32', ... at ...>

66. >>> cdll.advapi32.RegCloseKey
<_FuncPtr object at 0x...>

67. >>> a = cdll.advapi32
>>> RegCloseKey = a.RegCloseKey
>>> RegCloseKey(0)
6

68. no introspection

69. >>> RegCloseKey(0)
6
>>> RegCloseKey()
6

70. return value

71. function arguments

73. from ctypes import cdll
from ctypes import c_long, c_ulong
# WINADVAPI LONG WINAPI RegCloseKey(HKEY);
RegCloseKey = cdll.advapi32.RegCloseKey
RegCloseKey.restype = c_long
RegCloseKey.argtypes = [c_ulong]

74. from ctypes import cdll
from ctypes import c_long, c_ulong
# WINADVAPI LONG WINAPI RegCloseKey(HKEY);
RegCloseKey = cdll.advapi32.RegCloseKey
RegCloseKey.restype = c_long
RegCloseKey.argtypes = [c_ulong]

75. from ctypes import cdll
from ctypes import c_long, c_ulong
# WINADVAPI LONG WINAPI RegCloseKey(HKEY);
RegCloseKey = cdll.advapi32.RegCloseKey
RegCloseKey.restype = c_long
RegCloseKey.argtypes = [c_ulong]

76. from ctypes import cdll
from ctypes import c_long, c_ulong
LONG = c_long
HANDLE = c_ulong # in header files: void *
HKEY = HANDLE
# WINADVAPI LONG WINAPI RegCloseKey(HKEY);
RegCloseKey = cdll.advapi32.RegCloseKey
RegCloseKey.restype = LONG
RegCloseKey.argtypes = [HKEY]

77. >>> RegCloseKey(0)
6
>>> RegCloseKey()
Traceback (most recent call last):
...
TypeError: this function takes at
least 1 argument (0 given)

78. not Pythonic

80. PyHKEY.Close()
Closes the underlying
Windows handle.

81. class PyHKEY(object):
def __init__(self, hkey):
self.hkey = hkey
def Close(self):
if RegCloseKey(self.hkey) != 0:
raise WindowsError()
self.hkey = 0
class WindowsError(OSError):
...

82. class PyHKEY(object):
def __init__(self, hkey):
self.hkey = hkey
def Close(self):
RegCloseKey(self.hkey)
raise WindowsError()
self.hkey = 0
class WindowsError(OSError):
...

83. class PyHKEY(object):
def __init__(self, hkey):
self.hkey = hkey
def Close(self):
if RegCloseKey(self.hkey) != 0:
raise WindowsError()
self.hkey = 0
class WindowsError(OSError):
...

84. >>> from cygwinreg import PyHKEY
>>> hkey = PyHKEY(0)
>>> hkey.Close()

86. RegDeleteKeyW = cdll.advapi32.RegDeleteKeyW
RegDeleteKeyW.restype = LONG
RegDeleteKeyW.argtypes = [HKEY, LPCWSTR]

88. def DeleteKey(key, sub_key):
from cygwinreg.w32api import RegDeleteKeyW
wincall(RegDeleteKeyW(PyHKEY.make(key),
sub_key))

89. hours later

90. >>> try:
... import winreg
... except ImportError:
... import cygwinreg as winreg

91. def tradeoffs():

92. Python only

93. no compilation

94. slower

95. no parsing

96. simple

97. not automatic

98. standard

99. portable

100. good enough

101. def conclusion():

102. ~/akoha$ make check

103. continuous integration

104. browser tests

105. pypi.python.org/pypi/cygwinreg

106. no compilation

107. no installation

108. no :'-(

109. cygwinreg
pypi.python.org/pypi/cygwinreg
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this presentation:
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