code: def test_seg_patchmatch():
      # Create a node object
      seg_patchmatch = PatchMatch()
  
      # Check if the command is properly defined
      cmd = get_custom_path("seg_PatchMatch", env_dir="NIFTYSEGDIR")
      assert seg_patchmatch.cmd == cmd
  
      # test raising error with mandatory args absent
      with pytest.raises(ValueError):
          seg_patchmatch.run()
  
      # Assign some input data
      in_file = example_data("im1.nii")
      mask_file = example_data("im2.nii")
      db_file = example_data("db.xml")
      seg_patchmatch.inputs.in_file = in_file
      seg_patchmatch.inputs.mask_file = mask_file
      seg_patchmatch.inputs.database_file = db_file
  
      cmd_tmp = (
          "{cmd} -i {in_file} -m {mask_file} -db {db} -o {out_file}"
      )
      expected_cmd = cmd_tmp.format(
          cmd=cmd,
          in_file=in_file,
          mask_file=mask_file,
          db=db_file,
          out_file="im1_pm.nii.gz",
      )
  
      assert seg_patchmatch.cmdline == expected_cmd
  
imports: import pytest
  from ....testing import example_data
  from ...niftyreg import get_custom_path
  from ...niftyreg.tests.test_regutils import no_nifty_tool
  from ..None import PatchMatch
label_desc: Use image node_id 1 for calling a global function with example usage: test_seg_patchmatch() without return types