code: def test_stack_no_file_ext(in_paths):
      """Test for error raised when no file extension provided in output
      file."""
  
      # Test that out_path needs a file extension to be valid
      out_fi = "test_stack"
      with pytest.raises(
          ValueError,
          match="Please specify a valid file name for output.",
      ):
          stack_arr, stack_prof = es.stack(in_paths, out_path=out_fi)
  
file_path: earthpy/earthpy/tests/test_stack.py
imports: import os
  import numpy
  import pytest
  import earthpy.spatial
label_desc: Use image node_id 9 for calling a global function with example usage: test_stack_no_file_ext(in_paths) without return types