'Test the diff in both directions, validate they are the same and of opposite signs.'

def test_sign(self):

    v1 = '0.1'
    v2 = '0.2'
    self.assertTrue((version_diff(v1, v2) < 0), 'First    version    earlier    than    the    second    returns    negative.')
    self.assertTrue((version_diff(v2, v1) > 0), 'Second    version    earlier    than    the    first    returns    positive.')
    self.assertTrue((version_diff(v2, v2) == 0), 'First    version    equals    the    second    returns    0.')
