code: def test_no_constraints(self):
      prob = Rosenbrock()
      result = minimize(
          prob.fun,
          prob.x0,
          method="trust-constr",
          jac=prob.grad,
          hess=prob.hess,
      )
      result1 = minimize(
          prob.fun, prob.x0, method="L-BFGS-B", jac="2-point"
      )
      with pytest.warns(UserWarning):
          result2 = minimize(
              prob.fun, prob.x0, method="L-BFGS-B", jac="3-point"
          )
      assert_array_almost_equal(result.x, prob.x_opt, decimal=5)
      assert_array_almost_equal(result1.x, prob.x_opt, decimal=5)
      assert_array_almost_equal(result2.x, prob.x_opt, decimal=5)
  
imports: from __future__ import division, print_function, absolute_import
  import numpy
  import pytest
  from scipy.linalg import block_diag
  from scipy.sparse import csc_matrix
  from numpy.testing import TestCase, assert_array_almost_equal, assert_array_less, assert_allclose, assert_
  from pytest import raises
  from scipy.optimize import NonlinearConstraint, LinearConstraint, Bounds, minimize, BFGS, SR1
  from scipy._lib._numpy_compat import suppress_warnings
label_desc: Use image node_id 4 for calling the TestTrustRegionConstr obj's underlying member method code with example usage: obj.test_no_constraints() without return types