class_docstr: Tests for the generate_multi_shift_rule function
class_docstr_tok: ["Tests","for","the","generate_multi_shift_rule","function"]
docstr: Test that two independent 2-frequency parameters
  are correctly combined.
code: def test_two_frequency(self):
      """Test that two independent 2-frequency parameters
      are correctly combined."""
      c1 = (np.sqrt(2) + 1) / (4 * np.sqrt(2))
      c2 = (np.sqrt(2) - 1) / (4 * np.sqrt(2))
      f = [(1,), (0.5, 1)]
  
      res = generate_multi_shift_rule(f)
      expected = [
          [c1 * 0.5, np.pi / 2, np.pi / 2],
          [-c1 * 0.5, np.pi / 2, -np.pi / 2],
          [-c2 * 0.5, np.pi / 2, 3 * np.pi / 2],
          [c2 * 0.5, np.pi / 2, -3 * np.pi / 2],
          [-c1 * 0.5, -np.pi / 2, np.pi / 2],
          [c1 * 0.5, -np.pi / 2, -np.pi / 2],
          [c2 * 0.5, -np.pi / 2, 3 * np.pi / 2],
          [-c2 * 0.5, -np.pi / 2, -3 * np.pi / 2],
      ]
      assert np.allclose(res, expected)
  
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 4 for calling the TestMultiShiftRule obj's underlying member method code with example usage: obj.test_two_frequency() without return types