Precision of DateTime fields, when specified, do not match the DB schema

describe 'FactoryBot' do
  context 'when a DateTime field is specified with greater precision than allowed by the DB' do
    let(:nanosecond_precision_datetime) { DateTime.parse("2025-01-01T11:11:11.123456789") }
    let(:microsecond_precision_datetime) { DateTime.parse("2025-01-01T11:11:11.123456") }
    let(:identity) { create(:identity, updated_at: nanosecond_precision_datetime) }

    it 'does not truncate the DateTime to the DB precision until the record is reloaded' do
      expect(identity.updated_at).to eq(nanosecond_precision_datetime)
      identity.reload
      expect(identity.updated_at).to eq(microsecond_precision_datetime)
    end
  end

  context "when a DateTime field's value is generated by FactoryBot / ActiveRecord" do
    let(:identity) { create(:identity) }

    it 'returns the same value both before and after reloading the record' do
      updated_at_before_reload = identity.updated_at
      expect(identity.updated_at).to eq(updated_at_before_reload)
      identity.reload
      expect(identity.updated_at).to eq(updated_at_before_reload)
    end
  end
end

ActiveRecord::Schema[7.0].define do
  create_table "identities", id: { type: :string, limit: 12 }, force: :cascade do |t|
     t.datetime "updated_at", precision: nil, null: false