def METHOD_NAME(self):
    # Tests autocorrelation_negative yields the correct result
    # under both possibilities
    # Test for case where there is a negative element
    x = np.array([1, 2, 3, 4, -1, -1])
    self.assertEqual(pints._diagnostics._autocorrelate_negative(x), 4)
    # Test for case with no negative elements
    x = np.array([1, 2, 3, 4, 1, 1])
    self.assertEqual(pints._diagnostics._autocorrelate_negative(x), 6)