react_component should work outside of views (#636)

The rails_context method previously assumed that the controller
and request view helper methods were present. This commit checks
that these methods are present before they're called.

Resolves: #634

app/helpers/react_on_rails_helper.rb

@@ -350,7 +350,7 @@ def rails_context(server_side:)
         i18nLocale: I18n.locale,
         i18nDefaultLocale: I18n.default_locale
       }
-      if request.present?
+      if defined?(request) && request.present?
         # Check for encoding of the request's original_url and try to force-encoding the
         # URLs as UTF-8. This situation can occur in browsers that do not encode the
         # entire URL as UTF-8 already, mostly on the Windows platform (IE11 and lower).
@@ -402,7 +402,7 @@ def send_tag_method(tag_method_name, args)
   end
 
   def in_mailer?
-    return false unless controller.present?
+    return false unless defined?(controller)
     return false unless defined?(ActionMailer::Base)
 
     controller.is_a?(ActionMailer::Base)

spec/dummy/spec/helpers/react_on_rails_helper_spec.rb

@@ -183,4 +183,23 @@
     it { is_expected.to be_an_instance_of ActiveSupport::SafeBuffer }
     it { is_expected.to eq hello_world }
   end
+
+  describe "#rails_context" do
+    before do
+      @rendering_extension = ReactOnRails.configuration.rendering_extension
+      ReactOnRails.configuration.rendering_extension = nil
+    end
+
+    it "should not throw an error if not in a view" do
+      class PlainClass
+        include ReactOnRailsHelper
+      end
+
+      ob = PlainClass.new
+      expect { ob.send(:rails_context, server_side: true) }.to_not raise_error
+      expect { ob.send(:rails_context, server_side: false) }.to_not raise_error
+    end
+
+    after { ReactOnRails.configuration.rendering_extension = @rendering_extension }
+  end
 end