feat: add tests & use case for From personalization

USE_CASES.md

@@ -8,6 +8,7 @@ This document provides examples for specific use cases. Please [open an issue](h
 - [Send a Single Email to Multiple Recipients](#send-a-single-email-to-multiple-recipients)
 - [Send a Single Email to a Single Recipient](#send-a-single-email-to-a-single-recipient)
 - [Send Multiple Emails to Multiple Recipients](#send-multiple-emails-to-multiple-recipients)
+- [Send Multiple Emails with Personalizations](#send-multiple-emails-with-personalizations)
 - [Transactional Templates](#transactional-templates)
     - [With Mail Helper Class](#with-mail-helper-class)
     - [Without Mail Helper Class](#without-mail-helper-class)
@@ -492,6 +493,63 @@ namespace Example
 }
 ```
 
+<a name="multipleemailspersonalization"></a>
+# Send Multiple Emails with Personalizations
+
+```csharp
+using SendGrid;
+using SendGrid.Helpers.Mail;
+using System;
+using System.Threading.Tasks;
+using System.Collections.Generic;
+
+namespace Example
+{
+    internal class Example
+    {
+        private static void Main()
+        {
+            Execute().Wait();
+        }
+
+        static async Task Execute()
+        {
+            var apiKey = Environment.GetEnvironmentVariable("NAME_OF_THE_ENVIRONMENT_VARIABLE_FOR_YOUR_SENDGRID_KEY");
+            var client = new SendGridClient(apiKey);
+            var from = new EmailAddress("test@example.com");
+            var subject = "Hello from Twilio SendGrid!";
+
+            // Note that the domain for all from addresses must match
+            var msg = new SendGridMessage();
+            msg.Subject = subject;
+            msg.AddContent(MimeType.Text, "Easy to use, even with C#!");
+            msg.SetFrom(from);
+
+            msg.Personalizations = new List<Personalization>() {
+                new Personalization() {
+                    Tos = new List<EmailAddress>() {
+                        new EmailAddress("test1@example.com")
+                    }
+                },
+                new Personalization() {
+                    Tos = new List<EmailAddress>() {
+                        new EmailAddress("test2@example.com")
+                    },
+                    From = new EmailAddress("test3@example.com")
+                },
+            };
+            var response = await client.SendEmailAsync(msg);
+
+            Console.WriteLine(msg.Serialize());
+            Console.WriteLine(response.StatusCode);
+            Console.WriteLine(response.Headers.ToString());
+            Console.WriteLine("\n\nPress any key to exit.");
+            Console.ReadLine();
+        }
+    }
+}
+```
+
 <a name="transactional-templates"></a>
 # Transactional Templates
 

tests/SendGrid.Tests/Integration.cs

@@ -592,6 +592,91 @@ public void TestCreateMultipleEmailsToMultipleRecipients()
             Assert.Equal("{\"from\":{\"name\":\"Example User\",\"email\":\"test@example.com\"},\"personalizations\":[{\"to\":[{\"email\":\"test1@example.com\"}],\"subject\":\"Test Subject1\",\"substitutions\":{\"-name-\":\"Name1\"}},{\"to\":[{\"email\":\"test2@example.com\"}],\"subject\":\"Test Subject2\",\"substitutions\":{\"-name-\":\"Name1\"}},{\"to\":[{\"email\":\"test3@example.com\"}],\"subject\":\"Test Subject3\",\"substitutions\":{\"-name-\":\"Name1\"}}],\"content\":[{\"type\":\"text/plain\",\"value\":\"Hello -name-\"}]}", msg5.Serialize());
         }
 
+        [Fact]
+        public void TestAddFrom()
+        {
+            // Personalization not passed in, Personalization does not exist
+            var msg = new SendGridMessage();
+            msg.AddTo(new EmailAddress("test001@example.com", "Example User"));
+            msg.SetFrom(new EmailAddress("test002@example.com", "Example User"));
+            Assert.Equal("{\"from\":{\"name\":\"Example User\",\"email\":\"test002@example.com\"},\"personalizations\":[{\"to\":[{\"name\":\"Example User\",\"email\":\"test001@example.com\"}]}]}", msg.Serialize());
+
+            // Personalization passed in, no Personalizations
+            msg = new SendGridMessage();
+            var toEmail = new EmailAddress("test002@example.com", "Example User");
+            var fromEmail = new EmailAddress("test001@example.com", "Example User");
+            var personalization = new Personalization()
+            {
+                Tos = new List<EmailAddress>()
+                {
+                    toEmail
+                },
+                From = fromEmail
+            };
+            msg.AddTo(new EmailAddress("test003@example.com", "Example User"), 0, personalization);
+            Assert.Equal("{\"personalizations\":[{\"to\":[{\"name\":\"Example User\",\"email\":\"test002@example.com\"}," +
+                         "{\"name\":\"Example User\",\"email\":\"test003@example.com\"}]," +
+                         "\"from\":{\"name\":\"Example User\",\"email\":\"test001@example.com\"}}]}", msg.Serialize());
+
+            // Personalization passed in, Personalization exists
+            msg = new SendGridMessage();
+            toEmail = new EmailAddress("test004@example.com", "Example User");
+            fromEmail = new EmailAddress("test005@example.com", "Example User");
+            msg.Personalizations = new List<Personalization>() {
+                new Personalization() {
+                    Tos = new List<EmailAddress>()
+                    {
+                        toEmail
+                    },
+                    From = fromEmail
+                }
+            };
+            toEmail = new EmailAddress("test006@example.com", "Example User");
+            fromEmail = new EmailAddress("test007@example.com", "Example User");
+            personalization = new Personalization()
+            {
+                Tos = new List<EmailAddress>()
+                {
+                    toEmail
+                },
+                From = fromEmail
+            };
+            msg.AddTo(toEmail, 1, personalization);
+            Assert.Equal("{\"personalizations\":[{\"to\":[{\"name\":\"Example User\",\"email\":\"test004@example.com\"}]," +
+                         "\"from\":{\"name\":\"Example User\",\"email\":\"test005@example.com\"}}," +
+                         "{\"to\":[{\"name\":\"Example User\",\"email\":\"test006@example.com\"}]," +
+                         "\"from\":{\"name\":\"Example User\",\"email\":\"test007@example.com\"}}]}", msg.Serialize());
+
+
+            // Personalization not passed in Personalizations exists
+            msg = new SendGridMessage();
+            toEmail = new EmailAddress("test009@example.com", "Example User");
+            fromEmail = new EmailAddress("test010@example.com", "Example User");
+            msg.Personalizations = new List<Personalization>() {
+                new Personalization() {
+                    Tos = new List<EmailAddress>()
+                    {
+                        toEmail
+                    },
+                    From = fromEmail
+                }
+            };
+            toEmail = new EmailAddress("test011@example.com", "Example User");
+            fromEmail = new EmailAddress("test012@example.com", "Example User");
+            personalization = new Personalization()
+            {
+                Tos = new List<EmailAddress>()
+                {
+                    toEmail
+                },
+                From = fromEmail
+            };
+            msg.Personalizations.Add(personalization);
+            msg.AddTo(new EmailAddress("test013@example.com", "Example User"));
+            Assert.Equal("{\"personalizations\":[{\"to\":[{\"name\":\"Example User\",\"email\":\"test009@example.com\"},{\"name\":\"Example User\",\"email\":\"test013@example.com\"}]," +
+                         "\"from\":{\"name\":\"Example User\",\"email\":\"test010@example.com\"}},{\"to\":[{\"name\":\"Example User\",\"email\":\"test011@example.com\"}]," +
+                         "\"from\":{\"name\":\"Example User\",\"email\":\"test012@example.com\"}}]}", msg.Serialize());
+        }
         [Fact]
         public void TestAddTo()
         {