Description:

Adds a new Mutation to your application. Provide the mutation name as CamelCased or snake_cased.
 Pass a list of inputs as arguments with their types and if they are required or optional.
       This generates a mutation class in app/mutations.

Example:

rails generate mutation PumpTheJam technotronic:model:required space_jam:string:optional

This will create:
    app/mutations/pump_the_jam.rb
    spec/mutations/pump_the_jam_spec.rb