First version of a cop

.rubocop.yml

@@ -0,0 +1,3 @@
+Naming/FileName:
+ Exclude:
+   - lib/rubocop-teamtailor.rb

Gemfile.lock

@@ -9,11 +9,11 @@ GEM
   specs:
     ast (2.4.2)
     diff-lcs (1.5.1)
-    json (2.7.4)
+    json (2.8.1)
     language_server-protocol (3.17.0.3)
     lint_roller (1.1.0)
     parallel (1.26.3)
-    parser (3.3.5.0)
+    parser (3.3.6.0)
       ast (~> 2.4.1)
       racc
     racc (1.8.1)
@@ -43,7 +43,7 @@ GEM
       rubocop-ast (>= 1.32.2, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 2.4.0, < 3.0)
-    rubocop-ast (1.32.3)
+    rubocop-ast (1.35.0)
       parser (>= 3.3.1.0)
     rubocop-performance (1.22.1)
       rubocop (>= 1.48.1, < 2.0)

README.md

@@ -1,4 +1,4 @@
-# Rubocop::Teamtailor
+# RuboCop::Teamtailor
 
 TODO: Delete this and the text below, and describe your gem
 
@@ -36,4 +36,4 @@ The gem is available as open source under the terms of the [MIT License](https:/
 
 ## Code of Conduct
 
-Everyone interacting in the Rubocop::Teamtailor project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/[USERNAME]/rubocop-teamtailor/blob/main/CODE_OF_CONDUCT.md).
+Everyone interacting in the RuboCop::Teamtailor project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/[USERNAME]/rubocop-teamtailor/blob/main/CODE_OF_CONDUCT.md).

Rakefile

@@ -2,34 +2,29 @@
 
 require "bundler/gem_tasks"
 require "rspec/core/rake_task"
-
-RSpec::Core::RakeTask.new(:spec)
-
 require "standard/rake"
 
 task default: %i[spec standard]
 
-require 'rspec/core/rake_task'
-
 RSpec::Core::RakeTask.new(:spec) do |spec|
-  spec.pattern = FileList['spec/**/*_spec.rb']
+  spec.pattern = FileList["spec/**/*_spec.rb"]
 end
 
-desc 'Generate a new cop with a template'
+desc "Generate a new cop with a template"
 task :new_cop, [:cop] do |_task, args|
-  require 'rubocop'
+  require "rubocop"
 
   cop_name = args.fetch(:cop) do
-    warn 'usage: bundle exec rake new_cop[Department/Name]'
+    warn "usage: bundle exec rake new_cop[Department/Name]"
     exit!
   end
 
   generator = RuboCop::Cop::Generator.new(cop_name)
 
   generator.write_source
   generator.write_spec
-  generator.inject_require(root_file_path: 'lib/rubocop/cop/teamtailor_cops.rb')
-  generator.inject_config(config_file_path: 'config/default.yml')
+  generator.inject_require(root_file_path: "lib/rubocop/cop/teamtailor_cops.rb")
+  generator.inject_config(config_file_path: "config/default.yml")
 
   puts generator.todo
 end

config/default.yml

@@ -0,0 +1,6 @@
+# Write it!
+
+Teamtailor/NoHasManyInActiveModelSerializer:
+  Description: "TODO: Write a description of the cop."
+  Enabled: true
+  VersionAdded: "<<next>>"

lib/rubocop-teamtailor.rb

@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 
-require 'rubocop'
+require "rubocop"
 
-require_relative 'rubocop/teamtailor'
-require_relative 'rubocop/teamtailor/version'
-require_relative 'rubocop/teamtailor/inject'
+require_relative "rubocop/teamtailor"
+require_relative "rubocop/teamtailor/version"
+require_relative "rubocop/teamtailor/inject"
 
 RuboCop::Teamtailor::Inject.defaults!
 
-require_relative 'rubocop/cop/teamtailor_cops'
+require_relative "rubocop/cop/teamtailor_cops"

lib/rubocop/cop/teamtailor/no_has_many_in_active_model_serializer.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Teamtailor
+      class NoHasManyInActiveModelSerializer < Base
+        MSG = "No embedding of records"
+
+        def_node_matcher :no_has_many?, <<~PATTERN
+          (send nil? :has_many ...)
+        PATTERN
+
+        def on_class(class_node)
+          return unless class_node.defined_module_name.end_with?("Serializer")
+          check_children(class_node)
+        end
+
+        private
+
+        def check_children(node)
+          if no_has_many?(node)
+            add_offense(node)
+          end
+
+          if node.respond_to?(:children)
+            node.children.each { |child| check_children(child) }
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/teamtailor_cops.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require_relative "teamtailor/no_has_many_in_active_model_serializer"

lib/rubocop/teamtailor.rb

@@ -1,16 +1,16 @@
 # frozen_string_literal: true
 
 require_relative "teamtailor/version"
+require "yaml"
 
 module RuboCop
   module Teamtailor
     class Error < StandardError; end
     # Your code goes here...
-    PROJECT_ROOT   = Pathname.new(__dir__).parent.parent.expand_path.freeze
-    CONFIG_DEFAULT = PROJECT_ROOT.join('config', 'default.yml').freeze
-    CONFIG         = YAML.safe_load(CONFIG_DEFAULT.read).freeze
+    PROJECT_ROOT = Pathname.new(__dir__).parent.parent.expand_path.freeze
+    CONFIG_DEFAULT = PROJECT_ROOT.join("config", "default.yml").freeze
+    CONFIG = YAML.safe_load(CONFIG_DEFAULT.read).freeze
 
     private_constant(:CONFIG_DEFAULT, :PROJECT_ROOT)
   end
 end
-

sig/rubocop/teamtailor.rbs

@@ -1,4 +1,4 @@
-module Rubocop
+module RuboCop
   module Teamtailor
     VERSION: String
     # See the writing guide of rbs: https://github.com/ruby/rbs#guides

spec/rubocop/cop/teamtailor/no_has_many_in_active_model_serializer_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Teamtailor::NoHasManyInActiveModelSerializer, :config do
+  let(:config) { RuboCop::Config.new }
+
+  context "when in a serializer" do
+    it "registers an offense when using `has_many`" do
+      expect_offense(<<~RUBY)
+        class FooSerializer < ActiveModel::Serializer
+          has_many :locations, embed: :ids
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Teamtailor/NoHasManyInActiveModelSerializer: No embedding of records
+        end
+      RUBY
+    end
+
+    it "registers an offense for all `has_many`" do
+      expect_offense(<<~RUBY)
+        class FooSerializer < ActiveModel::Serializer
+          has_many :locations, embed: :ids
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Teamtailor/NoHasManyInActiveModelSerializer: No embedding of records
+          has_many :users, embed: :ids
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Teamtailor/NoHasManyInActiveModelSerializer: No embedding of records
+        end
+      RUBY
+    end
+
+    it "does not register an offense `has_one`" do
+      expect_no_offenses(<<~RUBY)
+        class FooSerializer < ActiveModel::Serializer
+          attributes :location_ids
+        end
+      RUBY
+    end
+  end
+
+  context "when not in a serializer" do
+    it "does not register an offense when using has_many" do
+      expect_no_offenses(<<~RUBY)
+        class Foo
+          has_many :locations
+        end
+      RUBY
+    end
+  end
+end

spec/rubocop/teamtailor_spec.rb

@@ -1,11 +1,7 @@
 # frozen_string_literal: true
 
-RSpec.describe Rubocop::Teamtailor do
+RSpec.describe RuboCop::Teamtailor do
   it "has a version number" do
-    expect(Rubocop::Teamtailor::VERSION).not_to be nil
-  end
-
-  it "does something useful" do
-    expect(false).to eq(true)
+    expect(RuboCop::Teamtailor::VERSION).not_to be nil
   end
 end

spec/spec_helper.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
-require 'rubocop-teamtailor'
-require 'rubocop/rspec/support'
+require "rubocop-teamtailor"
+require "rubocop/rspec/support"
 
 RSpec.configure do |config|
   config.include RuboCop::RSpec::ExpectOffense