old_contents: from tempfile import NamedTemporaryFile
  
  from numpy.core import memmap
  from numpy import arange, allclose
  from numpy.testing import *
  
  import warnings
  
  class TestMemmap(NumpyTestCase):
      def setUp(self):
          self.tmpfp = NamedTemporaryFile(prefix='mmap')
          self.shape = (3,4)
          self.dtype = 'float32'
          self.data = arange(12, dtype=self.dtype)
          self.data.resize(self.shape)
  
      def test_roundtrip(self):
          # Write data to file
          fp = memmap(self.tmpfp, dtype=self.dtype, mode='w+',
                      shape=self.shape)
          fp[:] = self.data[:]
          del fp # Test __del__ machinery, which handles cleanup
  
          # Read data back from file
          newfp = memmap(self.tmpfp, dtype=self.dtype, mode='r',
                         shape=self.shape)
          assert allclose(self.data, newfp)
          assert_array_equal(self.data, newfp)
  
      def test_open_with_filename(self):
          fp = memmap(self.tmpfp, dtype=self.dtype, mode='w+',
                         shape=self.shape)
          fp[:] = self.data[:]
  
          memmap(self.tmpfp.name, dtype=self.dtype, mode='r',
                 shape=self.shape)
  
      def test_flush(self):
          fp = memmap(self.tmpfp, dtype=self.dtype, mode='w+',
                      shape=self.shape)
          fp[:] = self.data[:]
          fp.flush()
  
          warnings.simplefilter('ignore', DeprecationWarning)
          fp.sync()
          warnings.simplefilter('default', DeprecationWarning)
  
  if __name__ == '__main__':
      NumpyTest().run()
  
new_contents: from tempfile import NamedTemporaryFile, mktemp
  import os
  
  from numpy.core import memmap
  from numpy import arange, allclose
  from numpy.testing import *
  
  import warnings
  
  class TestMemmap(NumpyTestCase):
      def setUp(self):
          self.tmpfp = NamedTemporaryFile(prefix='mmap')
          self.shape = (3,4)
          self.dtype = 'float32'
          self.data = arange(12, dtype=self.dtype)
          self.data.resize(self.shape)
  
      def test_roundtrip(self):
          # Write data to file
          fp = memmap(self.tmpfp, dtype=self.dtype, mode='w+',
                      shape=self.shape)
          fp[:] = self.data[:]
          del fp # Test __del__ machinery, which handles cleanup
  
          # Read data back from file
          newfp = memmap(self.tmpfp, dtype=self.dtype, mode='r',
                         shape=self.shape)
          assert allclose(self.data, newfp)
          assert_array_equal(self.data, newfp)
  
      def test_open_with_filename(self):
          tmpname = mktemp('','mmap')
          fp = memmap(tmpname, dtype=self.dtype, mode='w+',
                         shape=self.shape)
          fp[:] = self.data[:]
          os.unlink(tmpname)
  
      def test_flush(self):
          fp = memmap(self.tmpfp, dtype=self.dtype, mode='w+',
                      shape=self.shape)
          fp[:] = self.data[:]
          fp.flush()
  
          warnings.simplefilter('ignore', DeprecationWarning)
          fp.sync()
          warnings.simplefilter('default', DeprecationWarning)
  
  if __name__ == '__main__':
      NumpyTest().run()
  
subject: Use mktemp as a last resort to fix the memmap tests that break under Windows.