code: def test_read_segments():
      # Test segment reading
      fobj = BytesIO()
      arr = np.arange(100, dtype=np.int16)
      fobj.write(arr.tobytes())
      _check_bytes(read_segments(fobj, [(0, 200)], 200), arr)
      _check_bytes(
          read_segments(fobj, [(0, 100), (100, 100)], 200), arr
      )
      _check_bytes(
          read_segments(fobj, [(0, 50), (100, 50)], 100),
          np.r_[arr[:25], arr[50:75]],
      )
      _check_bytes(
          read_segments(fobj, [(10, 40), (100, 50)], 90),
          np.r_[arr[5:25], arr[50:75]],
      )
      _check_bytes(read_segments(fobj, [], 0), arr[0:0])
      # Error conditions
      with pytest.raises(ValueError):
          read_segments(fobj, [], 1)
      with pytest.raises(ValueError):
          read_segments(fobj, [(0, 200)], 199)
      with pytest.raises(Exception):
          read_segments(fobj, [(0, 100), (100, 200)], 199)
  
imports: import time
  from functools import partial
  from io import BytesIO
  from itertools import product
  from threading import Lock, Thread
  import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from ..fileslice import _positive_slice, _simple_fileslice, calc_slicedefs, canonical_slicers, fileslice, fill_slicer, is_fancy, optimize_read_slicers, optimize_slicer, predict_shape, read_segments, slice2len, slice2outax, slicers2segments, strided_scalar, threshold_heuristic
label_desc: Use image node_id 20 for calling a global function with example usage: test_read_segments() without return types