Clone the repo and cd into the directory.
Load the runner into an irb instance
irb -r ./runner.rb
Install the pry gem, then load the runner into the pry instance.
gem install pry
pry -r ./runner.rb
From irb you can now call any of the day/part combinations with their test inputs
$irb> runner = Runner.new(day: 1, part: 1, test: true)
$irb> runner.perform
==> 7
If you make changes to the solution.rb file that you're working on, you can reload it without exiting the IRB instance.
$irb> runner.reload
==> true