public async Task SendNotification_EmailIsSendSucessfully()
        {
            if (Directory.Exists(this.pickupDirectoryLocation))
            {
                foreach (var file in Directory.GetFiles(this.pickupDirectoryLocation))
                {
                    File.Delete(file);
                }
            }
            else
            {
                Directory.CreateDirectory(this.pickupDirectoryLocation);
            }

            var sut = new EmailNotificationService(this.mailSettings);

            await sut.SendNotificationAsync(new Message(new Recipient("*****@*****.**"), "Subject123", "Body123"));

            var files = Directory.GetFiles(this.pickupDirectoryLocation);

            Assert.True(Directory.Exists(this.pickupDirectoryLocation));
            Assert.Single(files);

            string message = File.ReadAllText(files[0]);

            Assert.Contains("*****@*****.**", message);
            Assert.Contains("Subject123", message);
        }
        public void SendNotification_MessageNull_ArgumentNullException()
        {
            var sut = new EmailNotificationService(this.mailSettings);

            Assert.ThrowsAsync <ArgumentNullException>(() => sut.SendNotificationAsync(null));
        }