public async Task AddBlackhole(string s) { var prefix = Networking.Models.AddressPrefix.Parse(s); // see if already exists var exists = await _sut.GetBlackholesAsync().AnyAsync(b => b == prefix); // if so, remove it if (exists) { await _sut.DeleteBlackholeAsync(prefix); } // Assert it was removed Assert.False(await _sut.GetBlackholesAsync().AnyAsync(b => b == prefix)); // add it await _sut.AddBlackholeAsync(prefix); await Task.Delay(millisecondsDelay : 500); var a = await _sut.GetBlackholesAsync().ToListAsync(); // Assert it was added Assert.True(await _sut.GetBlackholesAsync().AnyAsync(b => b == prefix)); // delete it await _sut.DeleteBlackholeAsync(prefix); // Assert it was deleted Assert.False(await _sut.GetBlackholesAsync().AnyAsync(b => b == prefix)); // if it existed previously, put it back if (exists) { await _sut.AddBlackholeAsync(prefix); } }