docstr: Test to make sure the input is maintained by default.
          
docstr_tok: ["Test","to","make","sure","the","input","is","maintained","by","default","."]
code: def test_input_maintained(self):
      """Test to make sure the input is maintained by default."""
      dtype_tuple = self.io_dtypes[functions[self.func]]
      for dtype in dtype_tuple[0]:
          for test_shape, s, kwargs in self.test_data:
              input_array = dtype_tuple[1](test_shape, dtype)
  
              orig_input_array = input_array.copy()
  
              getattr(self.test_interface, self.func)(
                  input_array, s, **kwargs
              )
  
              self.assertTrue(
                  numpy.all(input_array == orig_input_array)
              )
  
imports: from pyfftw import interfaces, _supported_types, _all_types_np
  from .test_pyfftw_base import run_test_suites, np_fft
  from ._get_default_args import get_default_args
  from packaging.version import Version
  import unittest
  import numpy
  import warnings
  import copy
label_desc: Use image node_id 22 for calling the InterfacesNumpyFFTTestFFT obj's underlying member method code with example usage: obj.test_input_maintained() without return types