### Question:
CostManagementImpl implements CostManagementService { @Override public CommonResult getCostById(Integer id){ Cost cost = costMapper.getById(id); return CommonResult.success(cost); }  @Override CommonResult listAllCosts(); @Override CommonResult getCostById(Integer id); @Override CommonResult insertCost(Cost cost); @Override CommonResult updateCostById(Cost cost); @Override CommonResult deleteCostById(Integer id);  }### Answer:
@Test public void testGetCostById() throws Exception { }