Check if a question is enabled before validating it's answer (#753)

app/controllers/form_controller.rb

@@ -138,8 +138,15 @@ private
   end
 
   def question_is_required?(question)
-    CaseLog::OPTIONAL_FIELDS.exclude?(question.id) &&
-      @page.subsection.applicable_questions(@case_log).map(&:id).include?(question.id)
+    CaseLog::OPTIONAL_FIELDS.exclude?(question.id) && required_questions.include?(question.id)
+  end
+
+  def required_questions
+    @required_questions ||= begin
+      log = @case_log
+      log.assign_attributes(responses_for_page(@page))
+      @page.subsection.applicable_questions(log).select { |q| q.enabled?(log) }.map(&:id)
+    end
   end
 
   def question_missing_response?(responses_for_page, question)

spec/requests/form_controller_spec.rb

@@ -263,6 +263,33 @@ RSpec.describe FormController, type: :request do
             expect(whodunnit_actor.id).to eq(user.id)
           end
         end
+
+        context "when the question has a conditional question" do
+          context "and the conditional question is not enabled" do
+            context "but is applicable because it has an inferred check answers display value" do
+              let(:page_id) { "property_postcode" }
+              let(:valid_params) do
+                {
+                  id: case_log.id,
+                  case_log: {
+                    page: page_id,
+                    postcode_known: "0",
+                    postcode_full: "",
+                  },
+                }
+              end
+
+              before do
+                case_log.update!(postcode_known: 1, postcode_full: "NW1 8RR")
+                post "/logs/#{case_log.id}/form", params: valid_params
+              end
+
+              it "does not require you to answer that question" do
+                expect(response).to redirect_to("/logs/#{case_log.id}/do-you-know-the-local-authority")
+              end
+            end
+          end
+        end
       end
 
       context "with checkbox questions" do