public SendGridMailDeliveryServiceTests()
        {
            _globalSettings = new GlobalSettings
            {
                Mail =
                {
                    SendGridApiKey = "SendGridApiKey"
                }
            };

            _hostingEnvironment = Substitute.For <IWebHostEnvironment>();
            _logger             = Substitute.For <ILogger <SendGridMailDeliveryService> >();
            _sendGridClient     = Substitute.For <ISendGridClient>();

            _sut = new SendGridMailDeliveryService(
                _sendGridClient,
                _globalSettings,
                _hostingEnvironment,
                _logger
                );
        }
        public SendGridMailDeliveryServiceTests()
        {
            _globalSettings = new GlobalSettings();

            _sut = new SendGridMailDeliveryService(_globalSettings);
        }