code: def test_sfm_background():
      fdata, fbvals, fbvecs = dpd.get_fnames()
      data = load_nifti_data(fdata)
      gtab = grad.gradient_table(fbvals, fbvecs)
      to_fit = data[0, 0, 0]
      to_fit[gtab.b0s_mask] = 0
      sfmodel = sfm.SparseFascicleModel(gtab, solver="NNLS")
      sffit = sfmodel.fit(to_fit)
      npt.assert_equal(sffit.beta, np.zeros_like(sffit.beta))
  
file_path: dipy/dipy/reconst/tests/test_sfm.py
imports: import warnings
  import numpy
  import numpy.testing
  import pytest
  import dipy.reconst.sfm
  import dipy.data
  import dipy.core.gradients
  import dipy.sims.voxel
  import dipy.core.optimize
  import dipy.reconst.cross_validation
  from dipy.io.gradients import read_bvals_bvecs
  from dipy.io.image import load_nifti_data
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 4 for calling a global function with example usage: test_sfm_background() without return types