From 9ffd1cc5a9237bbda94a87148bea14aa1544ec23 Mon Sep 17 00:00:00 2001
From: Tejas Bubane <tejasbubane@gmail.com>
Date: Sun, 31 May 2020 00:17:16 +0530
Subject: [PATCH] [Fix #8063] Add new `AllowedNames` option for
 `Naming/ClassAndModuleCamelCase`

Closes #8063
---
 CHANGELOG.md                                  |  1 +
 config/default.yml                            |  5 ++++
 docs/modules/ROOT/pages/cops_naming.adoc      | 20 ++++++++++++++-
 .../cop/naming/class_and_module_camel_case.rb | 12 ++++++++-
 .../class_and_module_camel_case_spec.rb       | 25 ++++++++++++++++---
 5 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fae20108e65..12e09889306 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 * [#8069](https://github.com/rubocop-hq/rubocop/issues/8069): New option for `expect_offense` to help format offense templates. ([@marcandre][])
 * [#7908](https://github.com/rubocop-hq/rubocop/pull/7908): Add new `Style/RedundantRegexpEscape` cop. ([@owst][])
 * [#7978](https://github.com/rubocop-hq/rubocop/pull/7978): Add new option `OnlyFor` to the `Bundler/GemComment` cop. ([@ric2b][])
+* [#8063](https://github.com/rubocop-hq/rubocop/issues/8063): Add new `AllowedNames` option for `Naming/ClassAndModuleCamelCase`. ([@tejasbubane][])
 
 ### Bug fixes
 
diff --git a/config/default.yml b/config/default.yml
index 2ae3ecf2aec..73231e26bce 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -2006,6 +2006,11 @@ Naming/ClassAndModuleCamelCase:
   StyleGuide: '#camelcase-classes'
   Enabled: true
   VersionAdded: '0.50'
+  VersionChanged: '0.85'
+  # Allowed class/module names can be specified here.
+  # These can be full or part of the name.
+  AllowedNames:
+    - module_parent
 
 Naming/ConstantName:
   Description: 'Constants should use SCREAMING_SNAKE_CASE.'
diff --git a/docs/modules/ROOT/pages/cops_naming.adoc b/docs/modules/ROOT/pages/cops_naming.adoc
index bba4fbd380d..b82e2a2ab8f 100644
--- a/docs/modules/ROOT/pages/cops_naming.adoc
+++ b/docs/modules/ROOT/pages/cops_naming.adoc
@@ -200,12 +200,18 @@ baz { |age, height, gender| do_stuff(age, height, gender) }
 | Yes
 | No
 | 0.50
-| -
+| 0.85
 |===
 
 This cop checks for class and module names with
 an underscore in them.
 
+`AllowedNames` config takes an array of permitted names.
+Its default value is `['module_parent']`.
+These names can be full class/module names or part of the name.
+eg. Adding `my_class` to the `AllowedNames` config will allow names like
+`my_class`, `my_class::User`, `App::my_class`, `App::my_class::User`, etc.
+
 === Examples
 
 [source,ruby]
@@ -221,8 +227,20 @@ class MyClass
 end
 module MyModule
 end
+class module_parent::MyModule
+end
 ----
 
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| AllowedNames
+| `module_parent`
+| Array
+|===
+
 === References
 
 * https://rubystyle.guide#camelcase-classes
diff --git a/lib/rubocop/cop/naming/class_and_module_camel_case.rb b/lib/rubocop/cop/naming/class_and_module_camel_case.rb
index e21ff27d6a6..7cde76bacf4 100644
--- a/lib/rubocop/cop/naming/class_and_module_camel_case.rb
+++ b/lib/rubocop/cop/naming/class_and_module_camel_case.rb
@@ -6,6 +6,12 @@ module Naming
       # This cop checks for class and module names with
       # an underscore in them.
       #
+      # `AllowedNames` config takes an array of permitted names.
+      # Its default value is `['module_parent']`.
+      # These names can be full class/module names or part of the name.
+      # eg. Adding `my_class` to the `AllowedNames` config will allow names like
+      # `my_class`, `my_class::User`, `App::my_class`, `App::my_class::User`, etc.
+      #
       # @example
       #   # bad
       #   class My_Class
@@ -18,11 +24,15 @@ module Naming
       #   end
       #   module MyModule
       #   end
+      #   class module_parent::MyModule
+      #   end
       class ClassAndModuleCamelCase < Cop
         MSG = 'Use CamelCase for classes and modules.'
 
         def on_class(node)
-          return unless /_/.match?(node.loc.name.source)
+          allowed = /#{cop_config['AllowedNames'].join('|')}/
+          name = node.loc.name.source.gsub(allowed, '')
+          return unless /_/.match?(name)
 
           add_offense(node, location: :name)
         end
diff --git a/spec/rubocop/cop/naming/class_and_module_camel_case_spec.rb b/spec/rubocop/cop/naming/class_and_module_camel_case_spec.rb
index 7b24e552aeb..eaa22fb863e 100644
--- a/spec/rubocop/cop/naming/class_and_module_camel_case_spec.rb
+++ b/spec/rubocop/cop/naming/class_and_module_camel_case_spec.rb
@@ -1,8 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe RuboCop::Cop::Naming::ClassAndModuleCamelCase do
-  subject(:cop) { described_class.new }
-
+RSpec.describe RuboCop::Cop::Naming::ClassAndModuleCamelCase, :config do
   it 'registers an offense for underscore in class and module name' do
     expect_offense(<<~RUBY)
       class My_Class
@@ -36,4 +34,25 @@ module Mine
       end
     RUBY
   end
+
+  it 'allows module_parent method' do
+    expect_no_offenses(<<~RUBY)
+      class module_parent::MyClass
+      end
+    RUBY
+  end
+
+  context 'custom allowed names' do
+    let(:cop_config) { { 'AllowedNames' => %w[getter_class setter_class] } }
+
+    it 'does not register offense for multiple allowed names' do
+      expect_no_offenses(<<~RUBY)
+        class getter_class::MyClass
+        end
+
+        class setter_class::MyClass
+        end
+      RUBY
+    end
+  end
 end