add file size to validation tracking

app/lib/upload_wrapper.rb

@@ -0,0 +1,14 @@
+class UploadWrapper
+  include ActiveSupport::NumberHelper
+
+  attr_reader :upload
+
+  def initialize(upload:)
+    @upload = upload
+  end
+
+  def as_json(*args)
+    r = super
+    r.merge(file_size: number_to_human_size(upload.size, strip_insignificant_zeros: false))
+  end
+end

app/models/concerns/validation_tracking.rb

@@ -41,6 +41,18 @@ def value_for_field(field)
     return if field == :base
     return if field.to_s.start_with?("section.")
 
-    public_send(field)
+    value = public_send(field)
+
+    if value.instance_of?(Array)
+      value = value.map do |upload|
+        if upload.instance_of?(ActionDispatch::Http::UploadedFile)
+          UploadWrapper.new(upload:)
+        else
+          upload
+        end
+      end
+    end
+
+    value
   end
 end

spec/lib/upload_wrapper_spec.rb

@@ -0,0 +1,15 @@
+require "rails_helper"
+
+RSpec.describe UploadWrapper do
+  describe "#as_json" do
+    subject(:upload_wrapper) do
+      described_class.new(upload:)
+    end
+
+    let(:upload) { file_fixture("upload1.pdf") }
+
+    it "includes file size" do
+      expect(upload_wrapper.as_json[:file_size]).to eql("4.98 KB")
+    end
+  end
+end

spec/models/concerns/validation_tracking_spec.rb

@@ -0,0 +1,40 @@
+require "rails_helper"
+
+RSpec.describe ValidationTracking do
+  let(:klass) do
+    Class.new do
+      include ActiveModel::Model
+      include ValidationTracking
+
+      attr_accessor :evidence_uploads
+
+      validate :field_with_meta_options
+
+      def self.model_name
+        ActiveModel::Name.new(self, nil, "referrals/allegation_evidence/upload_form")
+      end
+
+      def self.name
+        "Referrals::AllegationEvidence::UploadForm"
+      end
+
+      def field_with_meta_options
+        errors.add(:evidence_uploads, :file_size_too_big, max_allowed_file_size: "50MB")
+      end
+    end
+  end
+
+  describe "#track_validation_error" do
+    context "when an uploaded file" do
+      it "persists the file size" do
+        instance = klass.new(evidence_uploads: [ActionDispatch::Http::UploadedFile.new(tempfile: file_fixture("upload1.pdf"))])
+
+        expect do
+          instance.valid?
+        end.to change(ValidationError, :count).by(1)
+
+        expect(ValidationError.last.details.dig("evidence_uploads", "value", 0, "file_size")).to eql("4.98 KB")
+      end
+    end
+  end
+end