Add service generator

[citizen428]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Description

I'm currently a bit blocked on profile work, waiting for 2 PRs to get approved and merged. So in the meantime I did some work on a service generator to standardize our service objects a bit more.

Examples:

Generate a non-namespaced service without arguments

$ rails generate service DoTheThing

# app/services/do_the_thing.rb
class DoTheThing
  def self.call
    new.call
  end

  def call
  end
end

# spec/services/do_the_thing_spec.rb
require "rails_helper"

RSpec.describe DoTheThing, type: :service do
  pending "add some examples to (or delete) #{__FILE__}"
end

Generate a non-namespaced service with arguments:

$ rails generate service DoTheThing arg1 arg2

# app/services/do_the_thing.rb
class DoTheThing
  def self.call(arg1, arg2)
    new(arg1, arg2).call
  end

  def initialize(arg1, arg2)
    @arg1 = arg1
    @arg2 = arg2
  end

  def call
  end
end

The generated spec is the same as above.

Generate a namespaced service with arguments

$ rails generate service things/dothem arg1 arg2

# app/services/things/do_them.rb
class Things::DoThem
  def self.call(arg1, arg2)
    new(arg1, arg2).call
  end

  def initialize(arg1, arg2)
    @arg1 = arg1
    @arg2 = arg2
  end

  def call
  end
end

# spec/services/things/do_them_spec.rb
require "rails_helper"

RSpec.describe Things::DoThem, type: :service do
  pending "add some examples to (or delete) #{__FILE__}"
end

Related Tickets & Documents

n/a

QA Instructions, Screenshots, Recordings

Try the different examples above and verify that the generated code matches your expectations.

Added tests?

• Yes
• No, and this is why: there's surprisingly little documentation around testing generators with RSpec. The examples I found all use an external gem for this. I'm not sure I want to add this dependency just yet and we are also not testing the other generator. As this is a convenience tool for developers and not production code I think this is ok until I can evaluate testing strategies during the next cooldown.
• I need help with writing tests

Added to documentation?

• Docs.forem.com
• README
• No documentation needed

[rhymes]

Cool!

[rhymes]

@citizen428 the build is failing because of a naming issue:

/home/travis/build/forem/forem/vendor/bundle/ruby/2.7.0/gems/zeitwerk-2.4.0/lib/zeitwerk/loader/callbacks.rb:17:in `on_file_autoloaded': expected file /home/travis/build/forem/forem/lib/generators/service/service_generator.rb to define constant Generators::Service::ServiceGenerator, but didn't (Zeitwerk::NameError)

[citizen428]

@rhymes You caught me during lunch, I had already started working on this. The error you posted is a result of an attempt to fix it. Before it failed with this:

/home/travis/build/forem/forem/lib/generators/service/service_generator.rb:1:in `<main>': uninitialized constant Rails::Generators (NameError)

I was a bit dumbfounded, as we do everything the same way as in the data update generator. However, some googling seems to suggest that explicitly requiring rails/generators is the ThingToDo™ since Rails 3:

• [WARNING] Could not load generator "generators/devise/install_generator". Error: uninitialized constant Rails::Generators::Base. heartcombo/devise#2743
• require 'rails/generators' in import_generator.rb thoughtbot/refills#33
• Rails::Generators::Base, using github master branch with Rails 5, puma 3.8.2 in Heroku, Ruby 2.4.0, heroku-16 stack, I receive error. nsarno/knock#156
• https://stackoverflow.com/questions/14883897/uninitialized-constant-railsgenerators-nameerror/14884631#14884631

But this wasn't necessary for the DataUpdateGenerator... Anyway, adding it does lead to the error you mentioned above, which makes sense with how Zeitwerk loads constants.

[citizen428]

This made me believe we manually updated the autoload path for the other generator and that's indeed the case:

# config/initializers/zeitwerk.rb
# Ignoring folders that don't adhere to the new naming conventions
Rails.autoloaders.main.ignore(Rails.root.join("lib/data_update_scripts"))
Rails.autoloaders.main.ignore(Rails.root.join("lib/generators/data_update"))

I added a line for the new generator now.

[citizen428]

Oops, accidentally merge master back here instead of some other branch...

[Ridhwana]

Looks good, I just suggested a change for what looks like a typo.

[mstruve]

🔥