'Test the _write_borders() method'

def test_write_borders(self):

    xf_format = Format()
    xf_format.has_border = 1
    self.styles._set_style_properties([[xf_format], None, 0, 0, 1, 0, [], []])
    self.styles._write_borders()
    exp = '<borders    count="1"><border><left/><right/><top/><bottom/><diagonal/></border></borders>'
    got = self.fh.getvalue()
    self.assertEqual(got, exp)
