python 获取前三个交易日的日期 python获取三个月之前日期

最近转战金额业务，用sosotest进行接口自动化，需要使用python，涉及日期时间处理的一些好用的方法封装

#获取前后n个月的日期,前一个月monthValue=-1，后一个月monthValue=1
def getBeforeAfterMonthDate(dateStr, monthValue):
    fmt = '%Y%m%d'
    time_tuple = time.strptime(dateStr, fmt)
    year, month, day = time_tuple[:3]
    a_date = datetime.date(year, month, day)
 #   print(a_date, type(a_date))
  #  print(a_date)
    nextMonth = a_date + relativedelta(months = monthValue)
 #   print(nextMonth)
 #   print(nextMonth.strftime("%Y%m%d"))
    return nextMonth.strftime("%Y%m%d")#获取前后n天的日期
def getBeforeAfterDayDate(dateStr, dayValue):
    fmt = '%Y%m%d'
    time_tuple = time.strptime(dateStr, fmt)
    year, month, day = time_tuple[:3]
    a_date = datetime.date(year, month, day)
 #   print(a_date, type(a_date))
  #  print(a_date)
    nextMonth = a_date + relativedelta(days = dayValue)
 #   print(nextMonth)
 #   print(nextMonth.strftime("%Y%m%d"))
    return nextMonth.strftime("%Y%m%d")    #获取每个月的天数，dateStr为YYYYMMDD
def getDayCountForEachMonth(dateStr):
    fmt = '%Y%m%d'
    time_tuple = time.strptime(dateStr, fmt)
    year, month, day = time_tuple[:3]
    a_date = datetime.date(year, month, day)
    #print(year)
    #print(month)
    monthRange = calendar.monthrange(year, month)
  #  dayCount = calendar.monthlen(year, month)
    return monthRange[1]