[WHIT-2724] Fix minor inconsistencies in block_content

Make the data that is stored in block_content consistent with the original translations that it
is being copied from. Instead of directly getting the values from the edition, we instead use
the translation, so that we avoid getting fallback values and including data that is not part
of the original translation, or only relevant to the primary translation.

Also ensures we can't save anything in the `body` column for a StandardEdition, as we only care
about the value in block_content. This will hopefully prevent any confusion about where values
originate from.

Author: jamiestamp

app/models/concerns/edition/translatable.rb

@@ -5,10 +5,10 @@ class Trait < Edition::Traits::Trait
     def process_associations_before_save(edition)
       @edition.translations.each do |translation|
         I18n.with_locale(translation.locale) do
-          edition.title = @edition.title
-          edition.summary = @edition.summary
-          edition.body = @edition.body
-          edition.block_content = @edition.block_content
+          edition.title = translation.title
+          edition.summary = translation.summary
+          edition.body = translation.body
+          edition.write_attribute(:block_content, translation.block_content)
         end
       end
     end

app/models/standard_edition.rb

@@ -43,6 +43,10 @@ def body
     block_content["body"]
   end
 
+  def body=(_)
+    nil
+  end
+
   def can_set_previously_published?
     type_instance.settings["backdating_enabled"]
   end

test/unit/app/models/standard_edition_translation_block_content_consistency_test.rb

@@ -0,0 +1,252 @@
+require "test_helper"
+
+class StandardEditionTranslationBlockContentConsistencyTest < ActiveSupport::TestCase
+  def english_body_content = "English body content"
+  def translated_body_content(locale) = "Body content for #{locale}"
+
+  setup do
+    ConfigurableDocumentType.setup_test_types(
+      build_configurable_document_type(
+        "test", {
+          "schema" => {
+            "properties" => {
+              "body" => { "type" => "string", "format" => "govspeak", "title" => "Body" },
+              "image" => { "type" => "integer", "format" => "lead_image_select", "title" => "Lead image" },
+            },
+          },
+          "settings" => { "translations_enabled" => true },
+        }
+      ),
+    )
+  end
+
+  test "creating a new draft from a published StandardEdition with translations should not duplicate old body field data" do
+    translated_edition = create_standard_edition(translate_for: %w[cy])
+
+    new_draft = translated_edition.create_draft(create(:writer))
+
+    english_translation = new_draft.translation_for(:en)
+    welsh_translation = new_draft.translation_for(:cy)
+
+    assert_nil english_translation[:body],
+               "English translation body column should be nil, but got: #{english_translation[:body]}"
+    assert_nil welsh_translation[:body],
+               "Welsh translation body column should be nil, but got: #{welsh_translation[:body]}"
+
+    assert_equal english_body_content, english_translation.block_content["body"],
+                 "English body should be in block_content.body"
+    assert_equal translated_body_content("cy"), welsh_translation.block_content["body"],
+                 "Welsh body should be in block_content.body"
+  end
+
+  test "editions without images should not have image key in block_content" do
+    translated_edition = create_standard_edition(translate_for: %w[cy])
+
+    assert_not_includes translated_edition.translation_for(:en).block_content.keys, "image",
+                        "English translation should not have image key"
+    assert_not_includes translated_edition.translation_for(:cy).block_content.keys, "image",
+                        "Welsh translation should not have image key"
+
+    new_draft = translated_edition.create_draft(create(:writer))
+
+    assert_not_includes new_draft.translation_for(:en).block_content.keys, "image",
+                        "Draft English translation should not have image key"
+    assert_not_includes new_draft.translation_for(:cy).block_content.keys, "image",
+                        "Draft Welsh translation should not have image key"
+  end
+
+  test "primary translation with image should not clone image to non-primary translations" do
+    standard_edition = create_standard_edition(with_image: true)
+    create_translated_edition(standard_edition, locale: "cy", with_image: false)
+
+    english_translation = standard_edition.translation_for(:en)
+    welsh_translation = standard_edition.translation_for(:cy)
+    image_id = english_translation.block_content["image"]
+
+    assert_equal english_body_content, english_translation.block_content["body"],
+                 "English body should have correct content"
+    assert_equal translated_body_content("cy"), welsh_translation.block_content["body"],
+                 "Welsh body should have correct content"
+    assert_not_includes welsh_translation.block_content.keys, "image",
+                        "Welsh translation should not have image key"
+
+    new_draft = standard_edition.create_draft(create(:writer))
+
+    assert_equal image_id, new_draft.translation_for(:en).block_content["image"],
+                 "Draft English translation should have image value"
+    assert_equal english_body_content, new_draft.translation_for(:en).block_content["body"],
+                 "Draft English body should have correct content"
+
+    assert new_draft.translation_for(:cy).block_content["image"].blank?,
+           "Draft Welsh translation should not have a value but found Image ID: #{new_draft.translation_for(:cy).block_content['image']}"
+    assert_equal translated_body_content("cy"), new_draft.translation_for(:cy).block_content["body"],
+                 "Draft Welsh body should have correct content"
+  end
+
+  test "translated edition with image should not clone to primary translation" do
+    standard_edition = create_standard_edition(with_image: false)
+    create_translated_edition(standard_edition, locale: "cy", with_image: true)
+
+    english_translation = standard_edition.translation_for(:en)
+    welsh_translation = standard_edition.translation_for(:cy)
+    image_id = welsh_translation.block_content["image"]
+
+    new_draft = standard_edition.create_draft(create(:writer))
+
+    assert english_translation.block_content["image"].blank?,
+           "Draft English translation should not have image value"
+    assert_equal english_body_content, new_draft.translation_for(:en).block_content["body"],
+                 "Draft English body should have correct content"
+
+    assert_equal image_id, new_draft.translation_for(:cy).block_content["image"],
+                 "Draft Welsh translation should have image value"
+    assert_equal translated_body_content("cy"), new_draft.translation_for(:cy).block_content["body"],
+                 "Draft Welsh body should have correct content"
+  end
+
+  test "new draft editions with images get the translated image IDs from the parent" do
+    standard_edition = create_standard_edition(with_image: true)
+    create_translated_edition(standard_edition, locale: "cy", with_image: true)
+
+    english_image_id = standard_edition.translation_for(:en).block_content["image"]
+    welsh_image_id = standard_edition.translation_for(:cy).block_content["image"]
+
+    new_draft = standard_edition.create_draft(create(:writer))
+
+    assert_equal english_image_id, new_draft.translation_for(:en).block_content["image"],
+                 "Draft English translation should have image value"
+    assert_equal english_body_content, new_draft.translation_for(:en).block_content["body"],
+                 "Draft English body should have correct content"
+
+    assert_equal welsh_image_id, new_draft.translation_for(:cy).block_content["image"],
+                 "Draft Welsh translation should have image value"
+    assert_equal translated_body_content("cy"), new_draft.translation_for(:cy).block_content["body"],
+                 "Draft Welsh body should have correct content"
+  end
+
+  test "new draft with multiple translations each having images retains correct data per locale" do
+    standard_edition = create_standard_edition(with_image: true)
+    create_translated_edition(standard_edition, locale: "cy", with_image: true)
+    create_translated_edition(standard_edition, locale: "fr", with_image: true)
+
+    english_image_id = standard_edition.translation_for(:en).block_content["image"]
+    welsh_image_id = standard_edition.translation_for(:cy).block_content["image"]
+    french_image_id = standard_edition.translation_for(:fr).block_content["image"]
+
+    # Ensure all images are distinct
+    assert_not_equal english_image_id, welsh_image_id, "English and Welsh should have different images"
+    assert_not_equal english_image_id, french_image_id, "English and French should have different images"
+    assert_not_equal welsh_image_id, french_image_id, "Welsh and French should have different images"
+
+    new_draft = standard_edition.create_draft(create(:writer))
+
+    # Verify each locale retains its own image
+    assert_equal english_image_id, new_draft.translation_for(:en).block_content["image"],
+                 "Draft English translation should have its original image"
+    assert_equal welsh_image_id, new_draft.translation_for(:cy).block_content["image"],
+                 "Draft Welsh translation should have its original image"
+    assert_equal french_image_id, new_draft.translation_for(:fr).block_content["image"],
+                 "Draft French translation should have its original image"
+
+    # Verify body content is also correct per locale
+    assert_equal english_body_content, new_draft.translation_for(:en).block_content["body"],
+                 "Draft English body should have correct content"
+    assert_equal translated_body_content("cy"), new_draft.translation_for(:cy).block_content["body"],
+                 "Draft Welsh body should have correct content"
+    assert_equal translated_body_content("fr"), new_draft.translation_for(:fr).block_content["body"],
+                 "Draft French body should have correct content"
+  end
+
+  test "partial updates to block_content merge correctly within primary translation" do
+    draft_standard_edition = create_standard_edition(with_image: false, factory_name: :draft_standard_edition)
+
+    I18n.with_locale(:en) do
+      draft_standard_edition.block_content = { "image" => 123 }
+      draft_standard_edition.save!
+    end
+
+    draft_standard_edition.reload
+    primary_translation = draft_standard_edition.translation_for(:en)
+
+    assert_equal english_body_content, primary_translation.block_content["body"],
+                 "Body should be preserved after partial update"
+    assert_equal 123, primary_translation.block_content["image"],
+                 "Image should be added via partial update"
+  end
+
+  test "partial updates to block_content merge correctly within secondary translation" do
+    draft_standard_edition = create_standard_edition(with_image: false, factory_name: :draft_standard_edition)
+    create_translated_edition(draft_standard_edition, locale: "cy", with_image: false)
+
+    I18n.with_locale(:cy) do
+      draft_standard_edition.block_content = { "image" => 123 }
+      draft_standard_edition.save!
+    end
+
+    draft_standard_edition.reload
+    secondary_translation = draft_standard_edition.translation_for(:cy)
+
+    assert_equal translated_body_content(:cy), secondary_translation.block_content["body"],
+                 "Body should be preserved after partial update"
+    assert_equal 123, secondary_translation.block_content["image"],
+                 "Image should be added via partial update"
+  end
+
+  test "partial updates to block_content in translated locales do not affect primary translation" do
+    draft_standard_edition = create_standard_edition(with_image: false, factory_name: :draft_standard_edition)
+    create_translated_edition(draft_standard_edition, locale: "cy", with_image: false)
+
+    I18n.with_locale(:cy) do
+      draft_standard_edition.block_content = { "body" => "this is the updated translated version" }
+      draft_standard_edition.save!
+    end
+
+    draft_standard_edition.reload
+
+    primary_translation = draft_standard_edition.translation_for(:en)
+    assert_equal english_body_content, primary_translation.block_content["body"],
+                 "Body should be preserved after partial update"
+  end
+
+  test "partial updates to block_content in primary locale do not affect secondary translations" do
+    draft_standard_edition = create_standard_edition(with_image: false, factory_name: :draft_standard_edition)
+    create_translated_edition(draft_standard_edition, locale: "cy", with_image: false)
+
+    I18n.with_locale(:en) do
+      draft_standard_edition.block_content = { "body" => "this is the updated english version" }
+      draft_standard_edition.save!
+    end
+
+    draft_standard_edition.reload
+
+    secondary_translation = draft_standard_edition.translation_for(:cy)
+    assert_equal translated_body_content(:cy), secondary_translation.block_content["body"],
+                 "Body should be preserved after partial update"
+  end
+
+private
+
+  def create_standard_edition(with_image: false, translate_for: [], factory_name: :published_standard_edition)
+    block_content = { "body" => english_body_content }
+    block_content["image"] = create(:image).image_data.id if with_image
+
+    standard_edition = create(
+      factory_name,
+      configurable_document_type: "test",
+      title: "English title",
+      summary: "English summary",
+      block_content:,
+    )
+
+    translate_for.each { |locale| create_translated_edition(standard_edition, locale:) }
+
+    standard_edition
+  end
+
+  def create_translated_edition(standard_edition, locale:, with_image: false)
+    block_content = { "body" => translated_body_content(locale) }
+    block_content["image"] = create(:image).image_data.id if with_image
+
+    I18n.with_locale(locale) { standard_edition.translations.create!(locale:, block_content:) }
+  end
+end