Proof of concept for Shadow DOM Selenium issues
Demonstrates the limitations of the executeScript workaround for traversing shadow DOM elements in Selenium.
Simplified DOM (Angular adds some extra cruft)
<body>
<app-root>
<div>
<app-container id="container">
#shadow-root (open)
<app-select >
<input type="radio" id="yes" name="answer" value="yes">
<label for="yes">Yes</label><br>
<input type="radio" id="no" name="answer" value="no">
<label for="no">No</label><br>
<input type="radio" id="maybe" name="answer" value="maybe">
<label for="maybe">Maybe</label>
</app-select>
</app-container>
</div>
</app-root>
</body>The test has 2 cases:
- Expand the shadow dom and select the "No" radio button by ID (Passes)
- Expand the shadow dom and select the "No" radio button by XPATH (FAILS!)
def test_execute_script_id():
"""Attempt to select the radio button for 'No' within the shadow DOM by ID"""
driver = create_driver()
try:
container = WebDriverWait(driver, 30).until(EC.visibility_of_element_located((By.ID, 'container')))
shadow_root = expand_shadow_element(driver, container)
no_radio = shadow_root.find_element(By.ID, "no")
no_radio.click()
finally:
time.sleep(5)
driver.quit()
def test_execute_script_xpath():
"""Attempt to select the radio button for 'No' within the shadow DOM by XPATH"""
driver = create_driver()
try:
container = WebDriverWait(driver, 30).until(EC.visibility_of_element_located((By.ID, 'container')))
shadow_root = expand_shadow_element(driver, container)
no_radio = shadow_root.find_element(By.XPATH, ".//app-select//input[@value='no']")
no_radio.click()
finally:
time.sleep(10)
driver.quit()============================= test session starts ==============================
platform darwin -- Python 3.9.2, pytest-6.2.2, py-1.10.0, pluggy-0.13.1
rootdir: /Users/ngenereux/git/shadow-dom-poc/test
collected 2 items
test.py .F [100%]
=================================== FAILURES ===================================
__________________________ test_execute_script_xpath ___________________________
def test_execute_script_xpath():
driver = create_driver()
try:
container = WebDriverWait(driver, 30).until(EC.visibility_of_element_located((By.ID, 'container')))
shadow_root = expand_shadow_element(driver, container)
> no_radio = shadow_root.find_element(By.XPATH, ".//app-select//input[@value='no']")
test.py:41:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
.venv/lib/python3.9/site-packages/selenium/webdriver/remote/webelement.py:658: in find_element
return self._execute(Command.FIND_CHILD_ELEMENT,
.venv/lib/python3.9/site-packages/selenium/webdriver/remote/webelement.py:633: in _execute
return self._parent.execute(command, params)
.venv/lib/python3.9/site-packages/selenium/webdriver/remote/webdriver.py:321: in execute
self.error_handler.check_response(response)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <selenium.webdriver.remote.errorhandler.ErrorHandler object at 0x110e9b400>
response = {'status': 400, 'value': '{"value":{"error":"invalid selector","message":"invalid selector: Unable to locate an elemen...fff70d48109 _pthread_start + 148\\n24 libsystem_pthread.dylib 0x00007fff70d43b8b thread_start + 15\\n"}}'}
def check_response(self, response):
"""
Checks that a JSON response from the WebDriver does not have an error.
:Args:
- response - The JSON response from the WebDriver server as a dictionary
object.
:Raises: If the response contains an error message.
"""
status = response.get('status', None)
if status is None or status == ErrorCode.SUCCESS:
return
value = None
message = response.get("message", "")
screen = response.get("screen", "")
stacktrace = None
if isinstance(status, int):
value_json = response.get('value', None)
if value_json and isinstance(value_json, basestring):
import json
try:
value = json.loads(value_json)
if len(value.keys()) == 1:
value = value['value']
status = value.get('error', None)
if status is None:
status = value["status"]
message = value["value"]
if not isinstance(message, basestring):
value = message
message = message.get('message')
else:
message = value.get('message', None)
except ValueError:
pass
exception_class = ErrorInResponseException
if status in ErrorCode.NO_SUCH_ELEMENT:
exception_class = NoSuchElementException
elif status in ErrorCode.NO_SUCH_FRAME:
exception_class = NoSuchFrameException
elif status in ErrorCode.NO_SUCH_WINDOW:
exception_class = NoSuchWindowException
elif status in ErrorCode.STALE_ELEMENT_REFERENCE:
exception_class = StaleElementReferenceException
elif status in ErrorCode.ELEMENT_NOT_VISIBLE:
exception_class = ElementNotVisibleException
elif status in ErrorCode.INVALID_ELEMENT_STATE:
exception_class = InvalidElementStateException
elif status in ErrorCode.INVALID_SELECTOR \
or status in ErrorCode.INVALID_XPATH_SELECTOR \
or status in ErrorCode.INVALID_XPATH_SELECTOR_RETURN_TYPER:
exception_class = InvalidSelectorException
elif status in ErrorCode.ELEMENT_IS_NOT_SELECTABLE:
exception_class = ElementNotSelectableException
elif status in ErrorCode.ELEMENT_NOT_INTERACTABLE:
exception_class = ElementNotInteractableException
elif status in ErrorCode.INVALID_COOKIE_DOMAIN:
exception_class = InvalidCookieDomainException
elif status in ErrorCode.UNABLE_TO_SET_COOKIE:
exception_class = UnableToSetCookieException
elif status in ErrorCode.TIMEOUT:
exception_class = TimeoutException
elif status in ErrorCode.SCRIPT_TIMEOUT:
exception_class = TimeoutException
elif status in ErrorCode.UNKNOWN_ERROR:
exception_class = WebDriverException
elif status in ErrorCode.UNEXPECTED_ALERT_OPEN:
exception_class = UnexpectedAlertPresentException
elif status in ErrorCode.NO_ALERT_OPEN:
exception_class = NoAlertPresentException
elif status in ErrorCode.IME_NOT_AVAILABLE:
exception_class = ImeNotAvailableException
elif status in ErrorCode.IME_ENGINE_ACTIVATION_FAILED:
exception_class = ImeActivationFailedException
elif status in ErrorCode.MOVE_TARGET_OUT_OF_BOUNDS:
exception_class = MoveTargetOutOfBoundsException
elif status in ErrorCode.JAVASCRIPT_ERROR:
exception_class = JavascriptException
elif status in ErrorCode.SESSION_NOT_CREATED:
exception_class = SessionNotCreatedException
elif status in ErrorCode.INVALID_ARGUMENT:
exception_class = InvalidArgumentException
elif status in ErrorCode.NO_SUCH_COOKIE:
exception_class = NoSuchCookieException
elif status in ErrorCode.UNABLE_TO_CAPTURE_SCREEN:
exception_class = ScreenshotException
elif status in ErrorCode.ELEMENT_CLICK_INTERCEPTED:
exception_class = ElementClickInterceptedException
elif status in ErrorCode.INSECURE_CERTIFICATE:
exception_class = InsecureCertificateException
elif status in ErrorCode.INVALID_COORDINATES:
exception_class = InvalidCoordinatesException
elif status in ErrorCode.INVALID_SESSION_ID:
exception_class = InvalidSessionIdException
elif status in ErrorCode.UNKNOWN_METHOD:
exception_class = UnknownMethodException
else:
exception_class = WebDriverException
if value == '' or value is None:
value = response['value']
if isinstance(value, basestring):
if exception_class == ErrorInResponseException:
raise exception_class(response, value)
raise exception_class(value)
if message == "" and 'message' in value:
message = value['message']
screen = None
if 'screen' in value:
screen = value['screen']
stacktrace = None
if 'stackTrace' in value and value['stackTrace']:
stacktrace = []
try:
for frame in value['stackTrace']:
line = self._value_or_default(frame, 'lineNumber', '')
file = self._value_or_default(frame, 'fileName', '<anonymous>')
if line:
file = "%s:%s" % (file, line)
meth = self._value_or_default(frame, 'methodName', '<anonymous>')
if 'className' in frame:
meth = "%s.%s" % (frame['className'], meth)
msg = " at %s (%s)"
msg = msg % (meth, file)
stacktrace.append(msg)
except TypeError:
pass
if exception_class == ErrorInResponseException:
raise exception_class(response, message)
elif exception_class == UnexpectedAlertPresentException:
alert_text = None
if 'data' in value:
alert_text = value['data'].get('text')
elif 'alert' in value:
alert_text = value['alert'].get('text')
raise exception_class(message, screen, stacktrace, alert_text)
> raise exception_class(message, screen, stacktrace)
E selenium.common.exceptions.InvalidSelectorException: Message: invalid selector: Unable to locate an element with the xpath expression .//app-select//input[@value='no'] because of the following error:
E NotSupportedError: Failed to execute 'evaluate' on 'Document': The node provided is '#document-fragment', which is not a valid context node type.
E (Session info: chrome=89.0.4389.90)
.venv/lib/python3.9/site-packages/selenium/webdriver/remote/errorhandler.py:242: InvalidSelectorException
=========================== short test summary info ============================
FAILED test.py::test_execute_script_xpath - selenium.common.exceptions.Invali...
========================= 1 failed, 1 passed in 20.74s =========================