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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
"""Python environment for Windows a11y browser tests.
"""
import ctypes
import os
from ctypes import POINTER, byref
from ctypes.wintypes import BOOL, HWND, LPARAM, POINT # noqa: F401
from dataclasses import dataclass
import comtypes.automation
import comtypes.client
import psutil
from comtypes import COMError, IServiceProvider
CHILDID_SELF = 0
COWAIT_DEFAULT = 0
EVENT_OBJECT_FOCUS = 0x8005
GA_ROOT = 2
NAVRELATION_EMBEDS = 0x1009
OBJID_CLIENT = -4
RPC_S_CALLPENDING = -2147417835
WINEVENT_OUTOFCONTEXT = 0
WM_CLOSE = 0x0010
user32 = ctypes.windll.user32
oleacc = ctypes.oledll.oleacc
oleaccMod = comtypes.client.GetModule("oleacc.dll")
IAccessible = oleaccMod.IAccessible
del oleaccMod
# This is the path if running locally.
ia2Tlb = os.path.join(
os.getcwd(),
"..",
"..",
"..",
"accessible",
"interfaces",
"ia2",
"IA2Typelib.tlb",
)
if not os.path.isfile(ia2Tlb):
# This is the path if running in CI.
ia2Tlb = os.path.join(os.getcwd(), "ia2Typelib.tlb")
ia2Mod = comtypes.client.GetModule(ia2Tlb)
del ia2Tlb
# Shove all the IAccessible* interfaces and IA2_* constants directly
# into our namespace for convenience.
globals().update((k, getattr(ia2Mod, k)) for k in ia2Mod.__all__)
# We use this below. The linter doesn't understand our globals() update hack.
IAccessible2 = ia2Mod.IAccessible2
del ia2Mod
uiaMod = comtypes.client.GetModule("UIAutomationCore.dll")
globals().update((k, getattr(uiaMod, k)) for k in uiaMod.__all__)
uiaClient = comtypes.CoCreateInstance(
uiaMod.CUIAutomation._reg_clsid_,
interface=uiaMod.IUIAutomation,
clsctx=comtypes.CLSCTX_INPROC_SERVER,
)
TreeScope_Descendants = uiaMod.TreeScope_Descendants
UIA_AutomationIdPropertyId = uiaMod.UIA_AutomationIdPropertyId
del uiaMod
def AccessibleObjectFromWindow(hwnd, objectID=OBJID_CLIENT):
p = POINTER(IAccessible)()
oleacc.AccessibleObjectFromWindow(
hwnd, objectID, byref(IAccessible._iid_), byref(p)
)
return p
def getWindowClass(hwnd):
MAX_CHARS = 257
buffer = ctypes.create_unicode_buffer(MAX_CHARS)
user32.GetClassNameW(hwnd, buffer, MAX_CHARS)
return buffer.value
def getFirefoxHwnd():
"""Search all top level windows for the Firefox instance being
tested.
We search by window class name and window title prefix.
"""
# We can compare the grandparent process ids to find the Firefox started by
# the test harness.
commonPid = psutil.Process().parent().ppid()
# We need something mutable to store the result from the callback.
found = []
@ctypes.WINFUNCTYPE(BOOL, HWND, LPARAM)
def callback(hwnd, lParam):
if getWindowClass(hwnd) != "MozillaWindowClass":
return True
pid = ctypes.wintypes.DWORD()
user32.GetWindowThreadProcessId(hwnd, byref(pid))
if psutil.Process(pid.value).parent().ppid() != commonPid:
return True # Not the Firefox being tested.
found.append(hwnd)
return False
user32.EnumWindows(callback, LPARAM(0))
if not found:
raise LookupError("Couldn't find Firefox HWND")
return found[0]
def toIa2(obj):
serv = obj.QueryInterface(IServiceProvider)
return serv.QueryService(IAccessible2._iid_, IAccessible2)
def getDocIa2():
"""Get the IAccessible2 for the document being tested."""
hwnd = getFirefoxHwnd()
root = AccessibleObjectFromWindow(hwnd)
doc = root.accNavigate(NAVRELATION_EMBEDS, 0)
try:
child = toIa2(doc.accChild(1))
if "id:default-iframe-id;" in child.attributes:
# This is an iframe or remoteIframe test.
doc = child.accChild(1)
except COMError:
pass # No child.
return toIa2(doc)
def findIa2ByDomId(root, id):
search = f"id:{id};"
# Child ids begin at 1.
for i in range(1, root.accChildCount + 1):
child = toIa2(root.accChild(i))
if search in child.attributes:
return child
descendant = findIa2ByDomId(child, id)
if descendant:
return descendant
@dataclass
class WinEvent:
event: int
hwnd: int
objectId: int
childId: int
def getIa2(self):
acc = ctypes.POINTER(IAccessible)()
child = comtypes.automation.VARIANT()
ctypes.oledll.oleacc.AccessibleObjectFromEvent(
self.hwnd,
self.objectId,
self.childId,
ctypes.byref(acc),
ctypes.byref(child),
)
if child.value != CHILDID_SELF:
# This isn't an IAccessible2 object.
return None
return toIa2(acc)
class WaitForWinEvent:
"""Wait for a win event, usually for IAccessible2.
This should be used as follows:
1. Create an instance to wait for the desired event.
2. Perform the action that should fire the event.
3. Call wait() on the instance you created in 1) to wait for the event.
"""
def __init__(self, eventId, match):
"""event is the event id to wait for.
match is either None to match any object, an str containing the DOM id
of the desired object, or a function taking a WinEvent which should
return True if this is the requested event.
"""
self._matched = None
# A kernel event used to signal when we get the desired event.
self._signal = ctypes.windll.kernel32.CreateEventW(None, True, False, None)
# We define this as a nested function because it has to be a static
# function, but we need a reference to self.
@ctypes.WINFUNCTYPE(
None,
ctypes.wintypes.HANDLE,
ctypes.wintypes.DWORD,
ctypes.wintypes.HWND,
ctypes.wintypes.LONG,
ctypes.wintypes.LONG,
ctypes.wintypes.DWORD,
ctypes.wintypes.DWORD,
)
def winEventProc(hook, eventId, hwnd, objectId, childId, thread, time):
event = WinEvent(eventId, hwnd, objectId, childId)
if isinstance(match, str):
try:
ia2 = event.getIa2()
if f"id:{match};" in ia2.attributes:
self._matched = event
except (comtypes.COMError, TypeError):
pass
elif callable(match):
try:
if match(event):
self._matched = event
except Exception as e:
self._matched = e
if self._matched:
ctypes.windll.kernel32.SetEvent(self._signal)
self._hook = user32.SetWinEventHook(
eventId, eventId, None, winEventProc, 0, 0, WINEVENT_OUTOFCONTEXT
)
# Hold a reference to winEventProc so it doesn't get destroyed.
self._proc = winEventProc
def wait(self):
"""Wait for and return the desired WinEvent."""
# Pump Windows messages until we get the desired event, which will be
# signalled using a kernel event.
handles = (ctypes.c_void_p * 1)(self._signal)
index = ctypes.wintypes.DWORD()
TIMEOUT = 10000
try:
ctypes.oledll.ole32.CoWaitForMultipleHandles(
COWAIT_DEFAULT, TIMEOUT, 1, handles, ctypes.byref(index)
)
except WindowsError as e:
if e.winerror == RPC_S_CALLPENDING:
raise TimeoutError("Timeout before desired event received")
raise
finally:
user32.UnhookWinEvent(self._hook)
self._proc = None
if isinstance(self._matched, Exception):
raise self._matched from self._matched
return self._matched
def getDocUia():
"""Get the IUIAutomationElement for the document being tested."""
# We start with IAccessible2 because there's no efficient way to
# find the document we want with UIA.
ia2 = getDocIa2()
return uiaClient.ElementFromIAccessible(ia2, CHILDID_SELF)
def findUiaByDomId(root, id):
cond = uiaClient.CreatePropertyCondition(UIA_AutomationIdPropertyId, id)
# FindFirst ignores elements in the raw tree, so we have to use
# FindFirstBuildCache to override that, even though we don't want to cache
# anything.
request = uiaClient.CreateCacheRequest()
request.TreeFilter = uiaClient.RawViewCondition
return root.FindFirstBuildCache(TreeScope_Descendants, cond, request)
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