code: def test_set_join_node_file_input(tmpdir):
      """Test collecting join inputs to a set."""
      tmpdir.chdir()
      open("test.nii", "w+").close()
      open("test2.nii", "w+").close()
  
      # Make the workflow.
      wf = pe.Workflow(name="test")
      # the iterated input node
      inputspec = pe.Node(
          IdentityInterface(fields=["n"]), name="inputspec"
      )
      inputspec.iterables = [
          (
              "n",
              [
                  tmpdir.join("test.nii").strpath,
                  tmpdir.join("test2.nii").strpath,
              ],
          )
      ]
      # a pre-join node in the iterated path
      pre_join1 = pe.Node(
          IdentityInterface(fields=["n"]), name="pre_join1"
      )
      wf.connect(inputspec, "n", pre_join1, "n")
      # the set join node
      join = pe.JoinNode(
          PickFirst(),
          joinsource="inputspec",
          joinfield="in_files",
          name="join",
      )
      wf.connect(pre_join1, "n", join, "in_files")
  
      wf.run()
  
imports: import pytest
  from ....None import config
  from ...None import engine
  from ....interfaces import base
  from ....interfaces.utility import IdentityInterface, Function, Merge
  from ....interfaces.base import traits, File
label_desc: Use image node_id 11 for calling a global function with example usage: test_set_join_node_file_input(tmpdir) without return types