Add warning when user is about to delete condition with secondary skip

Currently (when branching is enabled) deleting a skip route for a
question that has a secondary skip route puts the form in a state where
there is a route with an error that can’t be deleted.

We do want users to be able to delete individual routes for a question.

So we’ve agreed that we will delete the secondary skip for a question
when deleting any other routes for that question. And we’ll let the user
know before the delete a route, with a warning.

This commit adds the warning; note that the deletion will take place in
forms-api, see alphagov/forms-api#686. To enable this we add a method
`#has_secondary_skip?` to the DeleteConfirmationInput object... I'm not
sure if this is the best place for this, but it'll do for now.

app/input_objects/pages/delete_condition_input.rb

@@ -18,6 +18,18 @@ def submit
   def goto_page_question_text
     return I18n.t("page_conditions.check_your_answers") if goto_page_id.nil? && record.skip_to_end
 
-    FormRepository.pages(form).filter { |p| p.id == goto_page_id }.first&.question_text
+    pages.filter { |p| p.id == goto_page_id }.first&.question_text
+  end
+
+  def has_secondary_skip?
+    check_page = pages.find(proc { raise "Cannot find page with id #{check_page_id}" }) { it.id == check_page_id }
+    page_conditions_service = PageConditionsService.new(form:, pages:, page: check_page)
+    page_conditions_service.check_conditions.any? { it != record && it.routing_page_id != it.check_page_id }
+  end
+
+private
+
+  def pages
+    @pages ||= FormRepository.pages(form)
   end
 end

app/views/pages/conditions/delete.html.erb

@@ -6,6 +6,10 @@
     <%= form_with(model: delete_condition_input, url: delete_condition_path(delete_condition_input.form.id, delete_condition_input.page.id, delete_condition_input.record.id), method: :delete) do |f| %>
       <% if delete_condition_input.errors.any? %>
         <%= f.govuk_error_summary %>
+      <% elsif delete_condition_input.has_secondary_skip? %>
+        <%= govuk_notification_banner(title_text: t("banner.default.title")) do |banner| %>
+          <% banner.with_heading(text: t(".any_other_answer_warning")) %>
+        <% end %>
       <% end %>
 
       <h1 class="govuk-heading-l">

config/locales/en.yml

@@ -1148,6 +1148,9 @@ en:
     your_form_is_live: Your form is live
   pages:
     answer_settings: Answer settings
+    conditions:
+      delete:
+        any_other_answer_warning: If you delete this route, the route for any other answer will also be deleted
     delete:
       notification_banner:
         end_of_route:

spec/input_objects/pages/delete_condition_input_spec.rb

@@ -68,4 +68,34 @@
       end
     end
   end
+
+  describe "#has_secondary_skip?" do
+    context "when the condition does not have a secondary skip condition" do
+      subject(:has_secondary_skip?) { delete_condition_input.has_secondary_skip? }
+
+      it { is_expected.to be false }
+    end
+
+    context "when the condition has a secondary skip condition" do
+      subject(:has_secondary_skip?) { delete_condition_input.has_secondary_skip? }
+
+      let(:condition) do
+        condition = build :condition, id: 1, routing_page_id: start_of_branches.id, check_page_id: start_of_branches.id, answer_value: "Wales", goto_page_id: start_of_second_branch.id
+        start_of_branches.routing_conditions << condition
+        condition
+      end
+
+      let(:start_of_branches) { pages.first }
+      let(:end_of_first_branch) { pages.second }
+      let(:start_of_second_branch) { pages.third }
+      let(:end_of_branches) { pages.last }
+
+      before do
+        secondary_skip_condition = build :condition, id: 2, routing_page_id: end_of_first_branch.id, check_page_id: start_of_branches.id, answer_value: nil, goto_page_id: end_of_branches.id
+        end_of_first_branch.routing_conditions << secondary_skip_condition
+      end
+
+      it { is_expected.to be true }
+    end
+  end
 end

spec/requests/pages/conditions_controller_spec.rb

@@ -295,7 +295,7 @@
   end
 
   describe "#delete" do
-    let(:condition) { build :condition, id: 1, routing_page_id: 1, check_page_id: 1, answer_value: "Wales", goto_page_id: 3 }
+    let(:condition) { build :condition, id: 1, routing_page_id: selected_page.id, check_page_id: selected_page.id, answer_value: "Wales", goto_page_id: 3 }
 
     before do
       selected_page.routing_conditions = [condition]

spec/views/pages/conditions/delete.html.erb_spec.rb

@@ -3,12 +3,14 @@
 describe "pages/conditions/delete.html.erb" do
   let(:delete_condition_input) { Pages::DeleteConditionInput.new(form:, page:, record: condition) }
   let(:form) { build :form, :ready_for_routing, id: 1 }
-  let(:condition) { build :condition, id: 1, routing_page_id: 1, check_page_id: 1, answer_value: "Wales", goto_page_id: pages.last.id }
+  let(:condition) { build :condition, id: 1, routing_page_id: pages.first.id, check_page_id: pages.first.id, answer_value: "Wales", goto_page_id: pages.last.id }
+  let(:secondary_skip_condition) { nil }
   let(:pages) { form.pages }
   let(:page) { pages.first }
 
   before do
     page.position = 1
+    secondary_skip_condition
     render template: "pages/conditions/delete", locals: { delete_condition_input: }
   end
 
@@ -43,4 +45,52 @@
       expect(rendered).to have_css ".govuk-error-summary"
     end
   end
+
+  context "when the condition does not have a secondary skip condition" do
+    let(:secondary_skip_condition) { nil }
+
+    it "does not render a warning" do
+      expect(rendered).not_to have_css ".govuk-notification-banner"
+    end
+  end
+
+  context "when the condition has a secondary skip condition" do
+    let(:condition) do
+      condition = build :condition, id: 1, routing_page_id: start_of_branches.id, check_page_id: start_of_branches.id, answer_value: "Wales", goto_page_id: start_of_second_branch.id
+      start_of_branches.routing_conditions << condition
+      condition
+    end
+
+    let(:secondary_skip_condition) do
+      condition = build :condition, id: 2, routing_page_id: end_of_first_branch.id, check_page_id: start_of_branches.id, answer_value: nil, goto_page_id: end_of_branches.id
+      end_of_first_branch.routing_conditions << condition
+      condition
+    end
+
+    let(:start_of_branches) { pages.first }
+    let(:end_of_first_branch) { pages.second }
+    let(:start_of_second_branch) { pages.third }
+    let(:end_of_branches) { pages.last }
+
+    it "renders a warning" do
+      expect(rendered).to have_css ".govuk-notification-banner", text: "If you delete this route, the route for any other answer will also be deleted"
+    end
+
+    context "when there is a validation error" do
+      let(:delete_condition_input) do
+        delete_condition_input = Pages::DeleteConditionInput.new(form:, page:, record: condition)
+        delete_condition_input.confirm = nil
+        delete_condition_input.validate
+        delete_condition_input
+      end
+
+      it "renders an error summary" do
+        expect(rendered).to have_css ".govuk-error-summary"
+      end
+
+      it "does not render a warning" do
+        expect(rendered).not_to have_css ".govuk-notification-banner", text: "If you delete this route, the route for any other answer will also be deleted"
+      end
+    end
+  end
 end