code: def test_default_header(self):
      # Check default header is as expected
      arr = np.arange(24, dtype=np.int16).reshape((2, 3, 4))
      img = self.image_class(arr, None)
      hdr = self.image_class.header_class()
      hdr.set_data_shape(arr.shape)
      hdr.set_data_dtype(arr.dtype)
      assert img.header == hdr
  
imports: from io import BytesIO
  import numpy
  import pytest
  from numpy.testing import assert_array_almost_equal
  from ..None import load
  from ..imageclasses import spatial_axes_first
  from ..spatialimages import HeaderDataError, SpatialHeader, SpatialImage
  from ..testing import bytesio_round_trip, expires, memmap_after_ufunc
  from ..tmpdirs import InTemporaryDirectory
label_desc: Use image node_id 4 for calling the TestSpatialImage obj's underlying member method code with example usage: obj.test_default_header() without return types