Add file_size to document details for PDF downloads

This change includes the file_size field in the document details
sent to the Publishing API, enabling the frontend to display
human-readable file sizes for downloadable PDF maps.

Author: GDSNewt

app/presenters/edition_presenter.rb

@@ -152,6 +152,7 @@ def document
                       "id" => SecureRandom.uuid,
                       "url" => edition.document["file_url"],
                       "content_type" => edition.document["content_type"],
+                      "file_size" => edition.document["size"],
                     }
                   end
   end

spec/presenters/edition_presenter_spec.rb

@@ -214,5 +214,45 @@
         expect(presented_data["last_edited_by_editor_id"]).to eq(user.uid)
       end
     end
+
+    describe "document field" do
+      let(:document_details) { presented_data["details"]["document"] }
+
+      context "when the edition has a document with size" do
+        before do
+          allow(edition).to receive(:document).and_return(
+            "file_url" => "https://assets.example.com/map.pdf",
+            "content_type" => "application/pdf",
+            "size" => 201_672,
+          )
+        end
+
+        it "includes the file size in the document details" do
+          expect(document_details).to include(
+            "file_size" => 201_672,
+            "url" => "https://assets.example.com/map.pdf",
+            "content_type" => "application/pdf",
+            "attachment_type" => "file",
+          )
+        end
+      end
+
+      context "when the edition has a document without size" do
+        before do
+          allow(edition).to receive(:document).and_return(
+            "file_url" => "https://assets.example.com/map.pdf",
+            "content_type" => "application/pdf",
+          )
+        end
+
+        it "includes file_size as nil when no size is provided" do
+          expect(document_details).to include(
+            "url" => "https://assets.example.com/map.pdf",
+            "content_type" => "application/pdf",
+            "file_size" => nil,
+          )
+        end
+      end
+    end
   end
 end