public async Task Given_Instance_When_ShortenAsync_Invoked_Then_It_Should_Return_Result()
{
var instance = new Mock <IUrl>();
instance.Setup(p => p.ShortenAsync()).ReturnsAsync(instance.Object);
var value = Task.FromResult(instance.Object);
var result = await UrlExtensions.ShortenAsync(value).ConfigureAwait(false);
result.Should().Be(instance.Object);
}