public void SendMessage_MessageWithAttachments_ShouldLogMessageToSend() { // Arrange // We need to configure NLog, because right now in NetHelper class we use it directly. // After migration to .Net Core we will be able to use ILogger<T> interface for logger. var configuration = new LoggingConfiguration(); var memoryTarget = new MemoryTarget { Name = "mem" }; configuration.AddTarget(memoryTarget); configuration.LoggingRules.Add(new LoggingRule("*", LogLevel.Trace, memoryTarget)); LogManager.Configuration = configuration; var parameters = new List <ModuleParameter> { new ModuleParameter { Name = "Messaging.Email.SmtpServer", Value = "smtp.domain.tld" }, new ModuleParameter { Name = "Messaging.Email.SmtpPort", Value = "25" } }; var netHelper = new NetHelper(parameters, ""); netHelper.AddAttachment("some.file", new byte[] { 0x00 }); // Act netHelper.SendMessage("*****@*****.**", "*****@*****.**", "subject", "message text"); // Assert var logs = memoryTarget.Logs; Assert.That(logs, Has.Some.Contains("going to send email")); }