Helper function for python tests to get rid of time.sleep

wait_for.py

import time
from typing import Callable, Iterable, TypeVar, Optional

T = TypeVar('T')


def wait_for(
    fn: Callable[..., T],
    message: str = "",
    messageSupplier: Optional[Callable[[], str]] = None,
    fnArgs: Optional[Iterable] = None,
    fnKwArgs: Optional[dict] = None,
    timeout: float = 4,
    interval: float = 0.1,
) -> T:
    """
        Wait for successful execution of function.

        Successful means:
        1. No exception was rised
        2. Returned value is converted to True.

        :param fn: Function to wait for
        :param message: TimeoutError message (is used if messageSupplier is None)
        :param messageSupplier: Function to create TimeoutError message
        :param fnArgs: Positional arguments to pass into fn
        :param fnKwArgs: Keyword arguments to pass into fn
        :param timeout: Waiting timeout
        :param interval: Interval between attempts to call fn
        :return: Value returned by fn
    """

    if fnArgs is None:
        fnArgs = tuple()
    if fnKwArgs is None:
        fnKwArgs = dict()
    lastError = None
    endTime = time.time() + timeout
    for i in range(int(timeout / interval) + 1):
        try:
            result = fn(*fnArgs, **fnKwArgs)
        except Exception as e:
            lastError = e
        else:
            lastError = None
            if result:
                return result

        if time.time() > endTime:
            break

        time.sleep(interval)

    msg = messageSupplier() if messageSupplier else message
    raise TimeoutError(msg=msg) from lastError