letter_opener_web VS rspec-rails

This gem makes sure you don’t embarrasingly send emails to real users whilst developing or testing, life-saver!

Also a note that might be obvious, but just in case: you really only want to use SendGrid in production. When you're developing locally you can use something like LetterOpener to view and test mail as needed.

When starting a Rails project, you have a lot of decisions to make. Whether or not to write tests should not be one of them. The big decision is to use Minitest or Rspec. Both of those testing frameworks are great and provide everything you need to test a Rails application thoroughly.

RSpec

rspec-rails factory_bot_rails faker

Ruby testing with RSpec

After all requests have been added, we need to cover them using request specs to ensure that everything will work as expected in the future as well. To add specs, we will use the rspec-rails gem. Our plan is to cover the 4 HTTP request methods that have been added above:

as a beginner you can skip it, just focus on understanding Rails' philosophy and getting comfortable with it. However, make sure you remember to come back to unit testing later bc it's a mandatory skill for a Rails developer. Unit test can help you understand your project's specs thoroughly (assume its test coverage is more than 90%). I recommend learning RSpec instead of Rails' built-in testing tool (the one being used in the Rails tutorial iirc)

RSpec is a testing framework for Ruby that is widely used in the Ruby on Rails community. It allows developers to write and execute automated tests. RSpec promotes behavior-driven development (BDD) by providing a readable syntax for describing the expected behavior of the application.

This is where rswag comes in. It is an extension to rspec-rails for "describing and testing API operations".