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

spec/serializers/rest/scheduled_status_serializer_spec.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe REST::ScheduledStatusSerializer do
+  subject do
+    serialized_record_json(
+      scheduled_status,
+      described_class
+    )
+  end
+
+  let(:account) { Fabricate(:account) }
+  let(:scheduled_status) { Fabricate.build(:scheduled_status, scheduled_at: 4.minutes.from_now, account: account) }
+
+  context 'with scheduled_at' do
+    it 'is serialized as RFC 3339 datetime' do
+      expect { DateTime.rfc3339(subject['scheduled_at']) }.to_not raise_error
+    end
+  end
+end