public void find_characteristic_by_key() {
when(dao.selectByKey("MEMORY_EFFICIENCY")).thenReturn(characteristicDto);
DefaultDebtCharacteristic characteristic = (DefaultDebtCharacteristic) service.characteristicByKey("MEMORY_EFFICIENCY");
assertThat(characteristic.id()).isEqualTo(1);
assertThat(characteristic.key()).isEqualTo("MEMORY_EFFICIENCY");
assertThat(characteristic.name()).isEqualTo("Memory use");
assertThat(characteristic.order()).isEqualTo(2);
assertThat(characteristic.parentId()).isNull();
assertThat(service.characteristicByKey("UNKNOWN")).isNull();