Is it correct to write dependencies in Gemfile?

[chiaraani]

I have just created a gem with bundler. I chose these options --test=rspec --linter=rubocop.
And I found out that rake, rspec and rubocop where in the Gemfile instead of the gemspec. I wonder if that is correct.

source "https://rubygems.org"

# Specify your gem's dependencies in gemspec
gemspec

gem "rake", "~> 13.0"

gem "rspec", "~> 3.0"

gem "rubocop", "~> 1.21"

[simi]

That's correct. Your runtime dependencies (as mentioned in the comment) should be in gemspec. But for dev dependencies (tools useful for development) it is common to keep them in Gemfile. Alternatively you can specify them in gemspec using add_development_dependency.