public async Task ReturnsAllTrackedEventNames()
        {
            var timestamp     = DateTime.UtcNow;
            var inputedEvents = new List <string>();

            for (var i = 1; i <= 5; i++)
            {
                await userActivity.Track("event-" + i, timestamp, i);
            }

            var outputedEvents = await userActivity.EventNames();

            inputedEvents.ForEach(n => Assert.Contains(n, outputedEvents));
        }