Prevent making Welsh live if the form has draft changes

We need to prevent Welsh forms being made live if there are changes to the English draft since the form was made live. If we don't, it's possible for a user to:

- make an English version of the form live
- make a change to that English version (e.g. adding or deleting a question)
- complete the Welsh translations for the form
- make the Welsh version live without making the English changes live

In this case the different language versions would be out of sync, as the English and Welsh form documents would be from before and after the change respectively. This would lead to unexpected behaviour for form fillers when switching languages.

Author: DavidBiddle

app/models/form.rb

@@ -232,6 +232,16 @@ def can_make_language_live?(language:)
     can_make_welsh_version_live? if language == "cy"
   end
 
+  def changed_from_live_version?(language:)
+    live_document = language == "cy" ? live_welsh_form_document : live_form_document
+    return false if live_document.blank?
+
+    ignored_keys = %w[live_at available_languages updated_at]
+    return false if live_document.content.except(*ignored_keys) == as_form_document(language:).except(*ignored_keys)
+
+    true
+  end
+
 private
 
   def set_external_id
@@ -296,7 +306,15 @@ def can_make_english_version_live?
   end
 
   def can_make_welsh_version_live?
-    has_live_version && all_ready_for_live? && welsh_completed? && live_form_document.present? && live_welsh_form_document.blank?
+    english_version_has_been_made_live? && !changed_from_live_version?(language: "en") && welsh_version_ready? && live_welsh_form_document.blank?
+  end
+
+  def english_version_has_been_made_live?
+    has_live_version && live_form_document.present?
+  end
+
+  def welsh_version_ready?
+    all_ready_for_live? && welsh_completed?
   end
 
   def after_archive

app/services/task_status_service.rb

@@ -142,8 +142,8 @@ def make_live_status
   end
 
   def make_only_english_live_status
+    return :completed if @form.has_live_version && !@form.changed_from_live_version?(language: "en")
     return :not_started if @form.can_make_language_live?(language: "en")
-    return :completed if @form.state == "live"
 
     :cannot_start
   end

spec/models/form_spec.rb

@@ -1644,7 +1644,7 @@
             context "when the Welsh task is still in progress" do
               let(:form) { create :form, :ready_for_live, :with_welsh_translation, state: "live", welsh_completed: false }
 
-              it "returns true" do
+              it "returns false" do
                 expect(form.can_make_language_live?(language:)).to be false
               end
             end
@@ -1655,6 +1655,36 @@
               it "returns true" do
                 expect(form.can_make_language_live?(language:)).to be true
               end
+
+              context "when there are changes which have not yet been made live on the English version" do
+                before do
+                  form.name = "A new form name"
+                  form.save_draft!
+
+                  form.share_preview_completed = true
+                  form.save_draft!
+                end
+
+                it "returns false" do
+                  expect(form.can_make_language_live?(language:)).to be false
+                end
+              end
+            end
+
+            context "when the Welsh task has been completed since the English form was made live" do
+              let(:form) { create :form, :ready_for_live, :with_welsh_translation, state: "live", welsh_completed: false }
+
+              before do
+                form.welsh_completed = true
+                form.save_draft!
+
+                form.share_preview_completed = true
+                form.save_draft!
+              end
+
+              it "returns true" do
+                expect(form.can_make_language_live?(language:)).to be true
+              end
             end
           end
 

spec/services/make_form_live_service_spec.rb

@@ -80,10 +80,10 @@
       let(:language) { "cy" }
 
       context "when the form has a live English version" do
-        let(:current_form) { create :form, :ready_for_live, :with_welsh_translation, state: "live" }
+        let(:current_form) { create :form, :ready_for_live, :with_welsh_translation}
 
         before do
-          create :form_document, :live, form: current_form, language: "en", content: current_form.as_form_document
+          current_form.make_english_version_live!
         end
 
         it "makes the Welsh form live" do

spec/services/task_status_service_spec.rb

@@ -399,11 +399,13 @@
     describe "make_only_english_live_status" do
       let(:can_make_english_live) { false }
       let(:can_make_welsh_live) { false }
+      let(:changed_from_live_version) { false }
 
       let(:form) { build(:form, :with_group, group:) }
 
       before do
         allow(form).to receive(:can_make_language_live?).with(language: "en").and_return(can_make_english_live)
+        allow(form).to receive(:changed_from_live_version?).with(language: "en").and_return(changed_from_live_version)
         allow(form).to receive(:can_make_language_live?).with(language: "cy").and_return(can_make_welsh_live)
       end
 
@@ -434,16 +436,28 @@
           end
         end
 
-        context "when the form is a draft" do
-          let(:form) { build(:form, :ready_for_live, :with_group, group:) }
+        context "when the form is live with draft" do
+          let(:form) { build(:form, :live_with_draft, :with_group, group:) }
 
-          it "returns cannot_start" do
-            expect(task_status_service.all_task_statuses[:make_only_english_live_status]).to eq :cannot_start
+          context "when there are changes from the English form document" do
+            let(:changed_from_live_version) { true }
+
+            it "returns cannot_start" do
+              expect(task_status_service.all_task_statuses[:make_only_english_live_status]).to eq :cannot_start
+            end
+          end
+
+          context "when there are no changes from the English form document" do
+            let(:changed_from_live_version) { false }
+
+            it "returns completed" do
+              expect(task_status_service.all_task_statuses[:make_only_english_live_status]).to eq :completed
+            end
           end
         end
 
-        context "when the form is live with draft" do
-          let(:form) { build(:form, :live_with_draft, :with_group, group:) }
+        context "when the form is a draft" do
+          let(:form) { build(:form, :ready_for_live, :with_group, group:) }
 
           it "returns cannot_start" do
             expect(task_status_service.all_task_statuses[:make_only_english_live_status]).to eq :cannot_start