use halt_on_fail in Guardfile

Guardfile

@@ -1,5 +1,13 @@
-guard :rspec do
-  watch(%r{spec/.+_spec.rb})
-  watch(%r{lib/(.+)\.rb})    { |m| "spec/lib/#{m[1]}_spec.rb" }
-  watch('spec/spec_helper.rb') { "spec" }
+group :specs, halt_on_fail: true do
+  guard :rspec, cmd: "bundle exec rspec", failed_mode: :keep do
+    watch(%r{spec/.+_spec.rb})
+    watch(%r{lib/(.+)\.rb})    { |m| "spec/lib/#{m[1]}_spec.rb" }
+    watch("spec/spec_helper.rb") { "spec" }
+  end
+
+  guard :rubocop, all_on_start: false, cli: "--rails" do
+    watch(%r{.+\.rb$}) { |m| m[0] }
+    watch(%r{(?:.+/)?\.rubocop\.yml$}) { |m| File.dirname(m[0]) }
+    watch(%r{(?:.+/)?\.rubocop_todo\.yml$}) { |m| File.dirname(m[0]) }
+  end
 end