+
+
+def wait_until_true(predicate, timeout=60, sleep=1, exception=None):
+ """Wait until callable predicate is evaluated as True
+
+ :param predicate: (func) callable deciding whether waiting should continue
+ :param timeout: (int) timeout in seconds how long should function wait
+ :param sleep: (int) polling interval for results in seconds
+ :param exception: exception instance to raise on timeout. If None is passed
+ (default) then WaitTimeout exception is raised.
+ """
+ try:
+ with Timer(timeout=timeout):
+ while not predicate():
+ time.sleep(sleep)
+ except exceptions.TimerTimeout:
+ if exception and issubclass(exception, Exception):
+ raise exception # pylint: disable=raising-bad-type
+ raise exceptions.WaitTimeout