old_contents: from netCDF4 import Dataset
  import numpy as np
  import sys, os, unittest, tempfile
  from numpy.testing import assert_array_equal
  
  FILE_NAME = tempfile.NamedTemporaryFile(suffix='.nc', delete=False).name
  dimsize = np.iinfo(np.int64).max # max unsigned 64 bit integer
  ndim = 100
  arrdata = np.random.randint(np.iinfo(np.uint8).min,np.iinfo(np.uint8).max,size=ndim)
  
  class test_cdf5(unittest.TestCase):
  
      def setUp(self):
          self.netcdf_file = FILE_NAME
          nc = Dataset(self.netcdf_file,'w',format='NETCDF3_64BIT_DATA')
          # create a 64-bit dimension
          d = nc.createDimension('dim',dimsize) # 64-bit dimension
          # create an 8-bit unsigned integer variable
          v = nc.createVariable('var',np.uint8,'dim')
          v[:ndim] = arrdata
          nc.close()
  
      def tearDown(self):
          # Remove the temporary files
          os.remove(self.netcdf_file)
  
      def runTest(self):
          """testing NETCDF3_64BIT_DATA format (CDF-5)"""
          f  = Dataset(self.netcdf_file, 'r')
          assert f.dimensions['dim'].size == dimsize
          assert_array_equal(arrdata, f.variables['var'][:ndim])
          f.close()
  
  if __name__ == '__main__':
      unittest.main()
  
new_contents: from netCDF4 import Dataset
  import numpy as np
  import sys, os, unittest, tempfile
  from numpy.testing import assert_array_equal
  
  FILE_NAME = tempfile.NamedTemporaryFile(suffix='.nc', delete=False).name
  dimsize = np.iinfo(np.int32).max*2 # only allowed in CDF5
  ndim = 100
  arrdata = np.random.randint(np.iinfo(np.uint8).min,np.iinfo(np.uint8).max,size=ndim)
  
  class test_cdf5(unittest.TestCase):
  
      def setUp(self):
          self.netcdf_file = FILE_NAME
          nc = Dataset(self.netcdf_file,'w',format='NETCDF3_64BIT_DATA')
          # create a 64-bit dimension
          d = nc.createDimension('dim',dimsize) # 64-bit dimension
          # create an 8-bit unsigned integer variable
          v = nc.createVariable('var',np.uint8,'dim')
          v[:ndim] = arrdata
          nc.close()
  
      def tearDown(self):
          # Remove the temporary files
          os.remove(self.netcdf_file)
  
      def runTest(self):
          """testing NETCDF3_64BIT_DATA format (CDF-5)"""
          f  = Dataset(self.netcdf_file, 'r')
          assert f.dimensions['dim'].size == dimsize
          assert_array_equal(arrdata, f.variables['var'][:ndim])
          f.close()
  
  if __name__ == '__main__':
      unittest.main()
  
subject: fix for failing test