Add department checking to Registry

lib/rubocop/cop/registry.rb

@@ -64,6 +64,11 @@ def without_department(department)
         with(without_department.values.flatten)
       end
 
+      # @return [Boolean] Checks if given name is department
+      def department?(name)
+        departments.include? name.to_sym
+      end
+
       def contains_cop_matching?(names)
         cops.any? { |cop| cop.match?(names) }
       end
@@ -179,6 +184,10 @@ def names
         cops.map(&:cop_name)
       end
 
+      def names_for_department(department)
+        cops.select { |cop| cop.department == department.to_sym }.map(&:cop_name)
+      end
+
       def ==(other)
         cops == other.cops
       end

spec/rubocop/cop/registry_spec.rb

@@ -340,4 +340,21 @@
       ]
     )
   end
+
+  describe '#department?' do
+    it 'returns true for department name' do
+      expect(registry.department?('Lint')).to be true
+    end
+
+    it 'returns false for other names' do
+      expect(registry.department?('Foo')).to be false
+    end
+  end
+
+  describe 'names_for_department' do
+    it 'returns array of cops for specified department' do
+      expect(registry.names_for_department('Lint'))
+        .to eq %w[Lint/BooleanSymbol Lint/DuplicateMethods]
+    end
+  end
 end