Add specs for Ruby literal key regexp

spec/scanners/ruby_key_literals_spec.rb

@@ -8,6 +8,42 @@
     Object.new.extend I18n::Tasks::Scanners::RubyKeyLiterals
   end
 
+  describe '#literal_re' do
+    subject do
+      /(#{scanner.literal_re})/x =~ key
+      Regexp.last_match(1)
+    end
+
+    context 'string' do
+      context 'single quoted' do
+        let(:key) { %('some_key') }
+        it { is_expected.to eq(key) }
+      end
+
+      context 'double quoted' do
+        let(:key) { %q("#{some_key}") } # rubocop:disable Lint/InterpolationCheck
+        it { is_expected.to eq(key) }
+      end
+    end
+
+    context 'symbol' do
+      context 'regular literal' do
+        let(:key) { %(:some_key) }
+        it { is_expected.to eq(key) }
+      end
+
+      context 'single quoted' do
+        let(:key) { %(:'some_key') }
+        it { is_expected.to eq(key) }
+      end
+
+      context 'double quoted' do
+        let(:key) { %q(:"#{some_key}") } # rubocop:disable Lint/InterpolationCheck
+        it { is_expected.to eq(key) }
+      end
+    end
+  end
+
   describe '#valid_key?' do
     it 'allows forward slash in key' do
       expect(scanner).to be_valid_key('category/product')