class_docstr: Test that errors are raised e.g. for invalid inputs.
docstr: Tests that an error is raised if ``_reconstruct_equ`` receives a
  negative or non-integer ``num_frequency`` .
docstr_tok: ["Tests","that","an","error","is","raised","if","``","_reconstruct_equ","``","receives","a","negative","or","non-integer","``","num_frequency","``","."]
code: def test_num_frequency_invalid(self, num_frequency):
      """Tests that an error is raised if ``_reconstruct_equ`` receives a
      negative or non-integer ``num_frequency`` ."""
      with pytest.raises(
          ValueError,
          match="num_frequency must be a non-negative integer",
      ):
          _reconstruct_equ(dummy_qnode, num_frequency=num_frequency)
  
imports: from inspect import signature
  from itertools import chain
  from functools import reduce
  import pytest
  import numpy
  import pennylane
  from pennylane import numpy
  from pennylane.fourier.reconstruct import _reconstruct_equ, _reconstruct_gen, _prepare_jobs, reconstruct
  from pennylane.fourier.utils import join_spectra
label_desc: Use image node_id 2 for calling the TestErrors obj's underlying member method code with example usage: obj.test_num_frequency_invalid(num_frequency) without return types