Make title errors use the correct translation

This ensures that when a title is missing, the correct translation
is used for the title field, rather than `Enter a title`

Author: pezholio

app/models/edition.rb

@@ -1,5 +1,12 @@
 class Edition < ApplicationRecord
-  validates :title, presence: true
+  include ApplicationHelper
+
+  validates :title, presence: {
+    message: lambda do |edition, _|
+      I18n.t("activerecord.errors.models.edition.blank",
+             attribute_with_indefinite_article: edition.title_name_with_indefinite_article)
+    end,
+  }
   validates :change_note, presence: true, if: :major_change?, on: :change_note
   validates :major_change, inclusion: [true, false], on: :change_note
 
@@ -111,6 +118,12 @@ def is_deletable?
     can_transition?(:delete)
   end
 
+  def title_name_with_indefinite_article
+    attribute_key = "activerecord.attributes.edition/document.title.#{block_type || 'default'}"
+    attribute_name = I18n.t(attribute_key, default: I18n.t("activerecord.attributes.edition/document.title.default"))
+    add_indefinite_article(attribute_name.downcase)
+  end
+
 private
 
   def remove_destroyed(item)

config/locales/en.yml

@@ -49,8 +49,6 @@ en:
                   bands:
                     name:
                       blank: "Enter a band name"
-            title:
-              blank: "Enter a title"
             change_note:
               blank: "Enter a change note"
             lead_organisation_id:

spec/requests/workflow_spec.rb

@@ -333,7 +333,7 @@ def self.it_shows_the_correct_context
               }
 
           expect(response).to render_template("editions/workflow/edit_draft")
-          expect(page).to have_text(I18n.t("activerecord.errors.models.edition.attributes.title.blank"))
+          expect(page).to have_text(I18n.t("activerecord.errors.models.edition.blank", attribute_with_indefinite_article: "a title"))
         end
       end
     end

spec/unit/app/models/edition/edition_spec.rb

@@ -118,20 +118,30 @@
     end
   end
 
-  it "validates the presence of an edition title" do
-    edition = build(
-      :edition,
-      created_at:,
-      updated_at:,
-      details:,
-      document_attributes: {},
-      lead_organisation_id: organisation.id.to_s,
-      title: nil,
-    )
+  {
+    pension: "a title",
+    contact: "a contact name",
+    tax: "a tax name",
+    time_period: "a time period name",
+  }.each do |block_type, attribute_name|
+    context "when the edition is a #{block_type}" do
+      it "validates the presence of an edition title with the correct error message" do
+        edition = build(
+          :edition,
+          block_type,
+          created_at:,
+          updated_at:,
+          details:,
+          document: build(:document, block_type: block_type),
+          lead_organisation_id: organisation.id.to_s,
+          title: nil,
+        )
 
-    aggregate_failures do
-      expect_model_not_to_be_valid(model: edition)
-      expect(edition.errors.full_messages).to include("Enter a title")
+        aggregate_failures do
+          expect_model_not_to_be_valid(model: edition)
+          expect(edition.errors.full_messages).to include("Enter #{attribute_name}")
+        end
+      end
     end
   end