public void MergeIn_ThisFieldsAllSetAndOtherFieldsAllSet_ThisFieldsAllReplaced()
{
var settings1 = new EmailSettings(host: "mail.example.com", from: ExampleAddress1, to: ExampleAddress1);
var settings2 = new EmailSettings(host: "mail.example.com", from: ExampleAddress2, to: ExampleAddress2);
var result = settings1.MergeIn(settings2);
result.Host.ShouldBe("mail.example.com");
result.From.ShouldBe(ExampleAddress2);
result.To.ShouldBe(ExampleAddress2);
}