Write a function to calculate the sum of the negative numbers of a given list of numbers using lambda function.
def sum_negativenum(nums):
  sum_negativenum = list(filter(lambda nums:nums<0,nums))
  return sum(sum_negativenum)
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to calculate the sum of the negative numbers of a given list of numbers using lambda function.
def sum_negativenum(nums):
  sum_negativenum = list(filter(lambda nums:nums<0,nums))
  return sum(sum_negativenum)[/INST]assert sum_negativenum([2, 4, -6, -9, 11, -12, 14, -5, 17])==-32
assert sum_negativenum([10,15,-14,13,-18,12,-20])==-52
assert sum_negativenum([19, -65, 57, 39, 152,-639, 121, 44, 90, -190])==-894</s>