Source code for traits_futures.qt.gui_test_assistant
# (C) Copyright 2018-2020 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
"""
Test support, providing the ability to run the event loop from tests.
"""
from pyface.qt.QtCore import QTimer
from pyface.qt.QtGui import QApplication
#: Default timeout, in seconds
TIMEOUT = 10.0
[docs]class GuiTestAssistant:
[docs] def setUp(self):
qt_app = QApplication.instance()
if qt_app is None:
qt_app = QApplication([])
self.qt_app = qt_app
[docs] def run_until(self, object, trait, condition, timeout=TIMEOUT):
"""
Run event loop until the given condition holds true, or until timeout.
The condition is re-evaluated, with the object as argument, every time
the trait changes.
Parameters
----------
object : traits.has_traits.HasTraits
Object whose trait we monitor.
trait : str
Name of the trait to monitor for changes.
condition : callable
Single-argument callable, returning a boolean. This will be
called with *object* as the only input.
timeout : float, optional
Number of seconds to allow before timing out with an exception.
The (somewhat arbitrary) default is 10 seconds.
Raises
------
RuntimeError
If timeout is reached, regardless of whether the condition is
true or not at that point.
"""
qt_app = self.qt_app
timeout_in_ms = round(1000.0 * timeout)
timeout_timer = QTimer()
timeout_timer.setSingleShot(True)
timeout_timer.setInterval(timeout_in_ms)
def stop_on_timeout():
qt_app.exit(1)
def stop_if_condition():
if condition(object):
qt_app.exit(0)
object.on_trait_change(stop_if_condition, trait)
try:
# The condition may have become True before we
# started listening to changes. So start with a check.
if condition(object):
timed_out = 0
else:
timeout_timer.timeout.connect(stop_on_timeout)
timeout_timer.start()
try:
timed_out = qt_app.exec_()
finally:
timeout_timer.stop()
timeout_timer.timeout.disconnect(stop_on_timeout)
finally:
object.on_trait_change(stop_if_condition, trait, remove=True)
if timed_out:
raise RuntimeError(
"run_until timed out after {} seconds. "
"At timeout, condition was {}.".format(
timeout, condition(object)
)
)
