docstr: a value error should be raised if outlier is not >= 0
code: def test_outlier_geq_zero(self):
      """a value error should be raised if outlier is not >= 0"""
  
      Discretiser(method="outlier", outlier_percentile=0.0)
      Discretiser(method="outlier", outlier_percentile=-0.0)
      Discretiser(method="outlier", outlier_percentile=0.1)
      with pytest.raises(
          ValueError,
          match="outlier_percentile must be between 0 and 0.5",
      ):
          Discretiser(method="outlier", outlier_percentile=-0.0000001)
  
imports: import math
  import numpy
  import pytest
  from causalnex.discretiser import Discretiser
label_desc: Use image node_id 5 for calling the TestErrorHandling obj's underlying member method code with example usage: obj.test_outlier_geq_zero() without return types