class_docstr: Tests of input validation and output correctness of function `generate_shift_rule`.
class_docstr_tok: ["Tests","of","input","validation","and","output","correctness","of","function","`","generate_shift_rule","`","."]
docstr: Tests the correct four term shift rule is generated given non-integer frequencies using
  explicitly defined shifts.
code: def test_non_integer_frequency_custom_shifts(self):
      """Tests the correct four term shift rule is generated given non-integer frequencies using
      explicitly defined shifts."""
  
      frequencies = (1 / 3, 2 / 3, 4 / 3)
      custom_shifts = (
          np.pi / 4,
          np.pi / 3,
          2 * np.pi / 3,
      )
  
      correct_terms = [
          [1.7548361197453346, 0.7853981633974483],
          [-1.7548361197453346, -0.7853981633974483],
          [-0.8720240894718643, 1.0471975511965976],
          [0.8720240894718643, -1.0471975511965976],
          [0.016695190986336428, 2.0943951023931953],
          [-0.016695190986336428, -2.0943951023931953],
      ]
  
      generated_terms = generate_shift_rule(frequencies, custom_shifts)
  
      assert np.allclose(generated_terms, correct_terms)
  
imports: import pytest
  import numpy
  import pennylane
  from pennylane.gradients.general_shift_rules import eigvals_to_frequencies, frequencies_to_period, generate_shift_rule, _get_shift_rule, generate_multi_shift_rule, generate_shifted_tapes, generate_multishifted_tapes, _iterate_shift_rule_with_multipliers
label_desc: Use image node_id 8 for calling the TestGenerateShiftRule obj's underlying member method code with example usage: obj.test_non_integer_frequency_custom_shifts() without return types