def WaitForJavaScriptCondition(self, condition, **kwargs):
"""Wait for a JavaScript condition to become truthy.
Example: runner.WaitForJavaScriptCondition('window.foo == 10');
Args:
condition: The JavaScript condition (provided as string).
Optional keyword args:
timeout: The number in seconds to wait for the condition to become
True (default to 60).
context_id: The id of an iframe where to execute the code; the main page
has context_id=1, the first iframe context_id=2, etc.
Additional keyword arguments provide values to be interpolated within
the expression. See telemetry.util.js_template for details.
Returns:
The value returned by the JavaScript condition that got interpreted as
true.
Raises:
py_utils.TimeoutException
exceptions.EvaluationException
exceptions.WebSocketException
exceptions.DevtoolsTargetCrashException
"""
# Use the default both when timeout=None or the option is ommited.
timeout = kwargs.pop('timeout', None) or 60
context_id = kwargs.pop('context_id', None)
condition = js_template.Render(condition, **kwargs)
def IsJavaScriptExpressionTrue():
try:
return self._EvaluateJavaScript(condition, context_id, timeout)
except exceptions.EvaluationException:
# Eval may throw due to e.g. navigation.
return False
try:
return py_utils.WaitFor(IsJavaScriptExpressionTrue, timeout)
except py_utils.TimeoutException as e:
# Try to make timeouts a little more actionable by dumping console output.
debug_message = None
try:
debug_message = (
'Console output:\n%s' %
self.GetCurrentConsoleOutputBuffer())
except Exception as e: # pylint: disable=broad-except
debug_message = (
'Exception thrown when trying to capture console output: %s' %
repr(e))
# Rethrow with the original stack trace for better debugging.
raise py_utils.TimeoutException, \
py_utils.TimeoutException(
'Timeout after %ss while waiting for JavaScript:' % timeout +
condition + '\n' + e.message + '\n' + debug_message), \
sys.exc_info()[2]
def RunAction(self, tab):
code = 'function(element) { return element != null; }'
try:
self.EvaluateCallback(tab,
code,
wait=True,
timeout_in_seconds=self.timeout)
except py_utils.TimeoutException as e:
# Rethrow with the original stack trace for better debugging.
raise py_utils.TimeoutException, \
py_utils.TimeoutException(
'Timeout while waiting for element.\n' + e.message), \
sys.exc_info()[2]
def WaitForJavaScriptCondition2(self, condition, **kwargs):
"""Wait for a JavaScript condition to become true.
Example: runner.WaitForJavaScriptCondition2('window.foo == 10');
Args:
condition: The JavaScript condition (provided as string).
Optional keyword args:
timeout: The number in seconds to wait for the condition to become
True (default to 60).
context_id: The id of an iframe where to execute the code; the main page
has context_id=1, the first iframe context_id=2, etc.
Additional keyword arguments provide values to be interpolated within
the expression. See telemetry.util.js_template for details.
Raises:
py_utils.TimeoutException
exceptions.EvaluationException
exceptions.WebSocketException
exceptions.DevtoolsTargetCrashException
"""
# Use the default both when timeout=None or the option is ommited.
timeout = kwargs.get('timeout') or 60
context_id = kwargs.get('context_id')
condition = js_template.Render(condition, **kwargs)
def IsJavaScriptExpressionTrue():
return bool(self._runtime.Evaluate(condition, context_id, timeout))
try:
py_utils.WaitFor(IsJavaScriptExpressionTrue, timeout)
except py_utils.TimeoutException as e:
# Try to make timeouts a little more actionable by dumping console output.
debug_message = None
try:
debug_message = ('Console output:\n%s' %
self.GetCurrentConsoleOutputBuffer())
except Exception as e:
debug_message = (
'Exception thrown when trying to capture console output: %s'
% repr(e))
raise py_utils.TimeoutException(e.message + '\n' + debug_message)
def WaitForJavaScriptExpression(self, expr, timeout):
"""Waits for the given JavaScript expression to be True.
This method is robust against any given Evaluation timing out.
Args:
expr: The expression to evaluate.
timeout: The number of seconds to wait for the expression to be True.
Raises:
py_utils.TimeoutException: On a timeout.
exceptions.Error: See EvaluateJavaScript() for a detailed list of
possible exceptions.
"""
def IsJavaScriptExpressionTrue():
try:
return bool(self.EvaluateJavaScript(expr))
except py_utils.TimeoutException:
# If the main thread is busy for longer than Evaluate's timeout, we
# may time out here early. Instead, we want to wait for the full
# timeout of this method.
return False
try:
py_utils.WaitFor(IsJavaScriptExpressionTrue, timeout)
except py_utils.TimeoutException as e:
# Try to make timeouts a little more actionable by dumping console output.
debug_message = None
try:
debug_message = (
'Console output:\n%s' %
self._inspector_backend.GetCurrentConsoleOutputBuffer())
except Exception as e:
debug_message = (
'Exception thrown when trying to capture console output: %s'
% repr(e))
raise py_utils.TimeoutException(e.message + '\n' + debug_message)
