class_docstr: Tests for the numeric computation of VJPs
class_docstr_tok: ["Tests","for","the","numeric","computation","of","VJPs"]
docstr: A None Jacobian returns a None VJP
docstr_tok: ["A","None","Jacobian","returns","a","None","VJP"]
code: def test_jacobian_is_none_single(self):
      """A None Jacobian returns a None VJP"""
  
      dy = np.array([[1.0, 2.0], [3.0, 4.0]])
      jac = None
  
      vjp = qml.gradients.compute_vjp_single(dy, jac)
      assert vjp is None
  
imports: from functools import partial
  import pytest
  import pennylane
  from pennylane import numpy
  from pennylane.gradients import param_shift
label_desc: Use image node_id 7 for calling the TestComputeVJP obj's underlying member method code with example usage: obj.test_jacobian_is_none_single() without return types