Can't run Rails test or make migrations

Hello I am following Michael Hart's Ruby on Rails tutorial, I am trying to run test but when I use the rails test command I get this response code:

migrations are pending. To resolve this issue, run: 
rails db:migrate  RAILS_ENV=test 

Can someone explain why I am running this command in the first place? Unfortunately running this command does not resolve the issue either, after running it I get the following output:

random numbers.... CreateUsers: migrating
--create_table(:users)
rails aborted!
StandardError: An error has occured this and all later migrations cancelled;

SQLLite3::SQLException: table "users" already exist 

I'm not sure why this error is occurring either. Any method to resolve these issues would be appreciated, thank you.