code: def test_gdtrix(self):
      _assert_inverts(
          sp.gdtrix,
          lambda a, b, x: mpmath.gammainc(b, b=a * x, regularized=True),
          2,
          [
              Arg(0, 1e3, inclusive_a=False),
              Arg(0, 1e3, inclusive_a=False),
              ProbArg(),
          ],
          rtol=1e-7,
          endpt_atol=[None, 1e-7, 1e-10],
      )
  
imports: import itertools
  import numpy
  from numpy.testing import assert_equal, assert_allclose
  import pytest
  import scipy.special
  from scipy.special._testutils import MissingModule, check_version, FuncData
  from scipy.special._mptestutils import Arg, IntArg, get_args, mpf2float, assert_mpmath_equal
label_desc: Use image node_id 8 for calling the TestCDFlib obj's underlying member method code with example usage: obj.test_gdtrix() without return types