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 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

@@ -296,7 +296,15 @@ 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? && welsh_version_ready? && live_welsh_form_document.blank?
+  end
+
+  def english_version_has_been_made_live?
+    !has_draft_version && has_live_version && live_form_document.present?
+  end
+
+  def welsh_version_ready?
+    all_ready_for_live? && welsh_completed?
   end
 
   def after_archive

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 +1655,20 @@
               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
           end