generated Users controller and User model, added some small Rspec test for testing attributes
checking existence of attributes for objects by using respond_to in Rspec + Validating presence of correct data for corresponding attributes
added length validation to Rspec test and user.db
Done email format validation using Regular Expression + Done email(username) uniqueness validation both object level(uniqueness:{case-sensitive:false} and database level(AddIndexToUsersEmail)
added bcrypt gem to Gemfile and installed it
adadded a password_digest column to the db users table &&  added the_secure_password() method (this method does a lot) and password length validation. Finally corresponding Rspec tests to test them