Adding a condition to Content CopyToPublishDirectory to validate that the file exists before trying to copy it to output, to keep the same functionality as it existed in PJ. In MSBuild world, without this condition, CopyToPublishDirectory will fail.

TestAssets/TestProjects/WebAppWithMissingFileInPublishOptions/Services/IEmailSender.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace WebApplication.Services
+{
+    public interface IEmailSender
+    {
+        Task SendEmailAsync(string email, string subject, string message);
+    }
+}

TestAssets/TestProjects/WebAppWithMissingFileInPublishOptions/Services/ISmsSender.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace WebApplication.Services
+{
+    public interface ISmsSender
+    {
+        Task SendSmsAsync(string number, string message);
+    }
+}

TestAssets/TestProjects/WebAppWithMissingFileInPublishOptions/Services/MessageServices.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace WebApplication.Services
+{
+    // This class is used by the application to send Email and SMS
+    // when you turn on two-factor authentication in ASP.NET Identity.
+    // For more details see this link https://go.microsoft.com/fwlink/?LinkID=532713
+    public class AuthMessageSender : IEmailSender, ISmsSender
+    {
+        public Task SendEmailAsync(string email, string subject, string message)
+        {
+            // Plug in your email service here to send an email.
+            return Task.FromResult(0);
+        }
+
+        public Task SendSmsAsync(string number, string message)
+        {
+            // Plug in your SMS service here to send a text message.
+            return Task.FromResult(0);
+        }
+    }
+}