Add disabled_all to DirectiveComment

lib/rubocop/directive_comment.rb

@@ -64,6 +64,11 @@ def enabled_all?
       !disabled? && all_cops?
     end
 
+    # Checks if this directive disables all cops
+    def disabled_all?
+      disabled? && all_cops?
+    end
+
     # Checks if all cops specified in this directive
     def all_cops?
       cops == 'all'

spec/rubocop/directive_comment_spec.rb

@@ -214,4 +214,32 @@
       end
     end
   end
+
+  describe '#disabled_all?' do
+    subject { directive_comment.disabled_all? }
+
+    context 'when enabled all cops' do
+      let(:text) { 'def foo # rubocop:enable all' }
+
+      it { is_expected.to eq false }
+    end
+
+    context 'when enabled specific cops' do
+      let(:text) { '# rubocop:enable Foo/Bar' }
+
+      it { is_expected.to eq false }
+    end
+
+    context 'when disabled all cops' do
+      let(:text) { '# rubocop:disable all' }
+
+      it { is_expected.to eq true }
+    end
+
+    context 'when disabled specific cops' do
+      let(:text) { '# rubocop:disable Foo/Bar' }
+
+      it { is_expected.to eq false }
+    end
+  end
 end