[Fix #2343] Groups of cops can be disabled in rubocop.yml

Using the cop type, it is now possible to do this:

    Style:
      Enabled: false
    Performance:
      Enabled: false

...and so on.

If there are settings for both a cop type and a cop of that type, then if
either of them has `Enabled: false`, the cop will be disabled, UNLESS it is
specified in an `--only` CLI argument.

CHANGELOG.md

@@ -52,6 +52,7 @@
 * [#1543](https://github.com/bbatsov/rubocop/issues/1543): `Style/WordArray` has both `percent` and `brackets` (which enforces the use of bracketed arrays for strings) styles. ([@alexdowad][])
 * `Style/SpaceAroundOperators` has `AllowForAlignment` config parameter which allows extra spaces on the left if they serve to align the operator with another. ([@alexdowad][])
 * `Style/SymbolArray` has both `percent` and `brackets` (which enforces the user of bracketed arrays for symbols) styles. ([@alexdowad][])
+* [#2343](https://github.com/bbatsov/rubocop/issues/2343): Entire cop types (or "departments") can be disabled using in .rubocop.yml using config like `Style: Enabled: false`. ([@alexdowad][])
 
 ### Bug Fixes
 

lib/rubocop/config.rb

@@ -3,6 +3,8 @@
 require 'delegate'
 require 'pathname'
 
+# rubocop:disable Metrics/ClassLength
+
 module RuboCop
   # This class represents the configuration of the RuboCop application
   # and all its cops. A Config is associated with a YAML configuration
@@ -78,6 +80,16 @@ def for_cop(cop)
     end
 
     def cop_enabled?(cop)
+      department = if cop.respond_to?(:cop_type)
+                     cop.cop_type.to_s.capitalize
+                   else
+                     cop.split('/')[-2]
+                   end
+
+      if (dept_config = self[department])
+        return false if dept_config['Enabled'] == false
+      end
+
       for_cop(cop).empty? || for_cop(cop)['Enabled']
     end
 

spec/rubocop/config_spec.rb

@@ -329,4 +329,38 @@
       end
     end
   end
+
+  describe '#cop_enabled?' do
+    context 'when an entire cop type is disabled' do
+      context 'but an individual cop is enabled' do
+        let(:hash) do
+          {
+            'Style' => { 'Enabled' => false },
+            'Style/TrailingWhitespace' => { 'Enabled' => true }
+          }
+        end
+
+        it 'still disables the cop' do
+          cop_class = RuboCop::Cop::Style::TrailingWhitespace
+          expect(configuration.cop_enabled?(cop_class)).to be false
+        end
+      end
+    end
+
+    context 'when an entire cop type is enabled' do
+      context 'but an individual cop is disabled' do
+        let(:hash) do
+          {
+            'Style' => { 'Enabled' => true },
+            'Style/TrailingWhitespace' => { 'Enabled' => false }
+          }
+        end
+
+        it 'still disables the cop' do
+          cop_class = RuboCop::Cop::Style::TrailingWhitespace
+          expect(configuration.cop_enabled?(cop_class)).to be false
+        end
+      end
+    end
+  end
 end