Ensure datetime/date are serialized to correct format (#33086)

spec/serializers/rest/report_serializer_spec.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe REST::ReportSerializer do
+  subject do
+    serialized_record_json(
+      report,
+      described_class
+    )
+  end
+
+  let(:status) { Fabricate(:status) }
+  let(:report) { Fabricate(:report, status_ids: [status.id]) }
+
+  context 'with created_at' do
+    it 'is serialized as RFC 3339 datetime' do
+      expect { DateTime.rfc3339(subject['created_at']) }.to_not raise_error
+    end
+  end
+
+  context 'with action_taken_at' do
+    let(:acting_account) { Fabricate(:account) }
+
+    before do
+      report.resolve!(acting_account)
+    end
+
+    it 'is serialized as RFC 3339 datetime' do
+      expect { DateTime.rfc3339(subject['action_taken_at']) }.to_not raise_error
+    end
+  end
+end