Stubbing calls to AWS in Rails tests

I use aws-sdk gem to deal with file uploads to S3 in my Rails application. I needed to add tests for the account logo upload and removal feature. I use Paperclip gem to do the file uploads.Typically, applications use file storage in test environment to avoid hitting AWS API but in this application I was constrained to not use file storage in test environment.Obviously I did not want to hit the AWS API during tests. I came up with a solution using a technique provided by aws-sdk gem.