class_docstr: Test the area helpers.
docstr: Test the np2str function.
code: def test_np2str(self):
      """Test the np2str function."""
      # byte object
      npbytes = np.bytes_("hej")
      assert hf.np2str(npbytes) == "hej"
  
      # single element numpy array
      np_arr = np.array([npbytes])
      assert hf.np2str(np_arr) == "hej"
  
      # scalar numpy array
      np_arr = np.array(npbytes)
      assert hf.np2str(np_arr) == "hej"
  
      # multi-element array
      npbytes = np.array([npbytes, npbytes])
      with pytest.raises(
          ValueError,
          match="Array is not a string type or is larger than 1",
      ):
          hf.np2str(npbytes)
  
      # non-array
      with pytest.raises(
          ValueError,
          match="Array is not a string type or is larger than 1",
      ):
          hf.np2str(5)
  
imports: import os
  import unittest
  from datetime import datetime
  from unittest import mock
  import dask.array
  import numpy
  import numpy.testing
  import pyresample.geometry
  import pytest
  import xarray
  from fsspec.implementations.memory import MemoryFile, MemoryFileSystem
  from pyproj import CRS
  from satpy.readers import FSFile
  from satpy.readers import utils
label_desc: Use image node_id 6 for calling the TestHelpers obj's underlying member method code with example usage: obj.test_np2str() without return types