code: def test_string_select(setup_path):
      # GH 2973
      with ensure_clean_store(setup_path) as store:
          df = DataFrame(
              np.random.default_rng(2).standard_normal((10, 4)),
              columns=Index(list("ABCD"), dtype=object),
              index=date_range("2000-01-01", periods=10, freq="B"),
          )
  
          # test string ==/!=
          df["x"] = "none"
          df.loc[df.index[2:7], "x"] = ""
  
          store.append("df", df, data_columns=["x"])
  
          result = store.select("df", "x=none")
          expected = df[df.x == "none"]
          tm.assert_frame_equal(result, expected)
  
          result = store.select("df", "x!=none")
          expected = df[df.x != "none"]
          tm.assert_frame_equal(result, expected)
  
          df2 = df.copy()
          df2.loc[df2.x == "", "x"] = np.nan
  
          store.append("df2", df2, data_columns=["x"])
          result = store.select("df2", "x!=none")
          expected = df2[isna(df2.x)]
          tm.assert_frame_equal(result, expected)
  
          # int ==/!=
          df["int"] = 1
          df.loc[df.index[2:7], "int"] = 2
  
          store.append("df3", df, data_columns=["int"])
  
          result = store.select("df3", "int=2")
          expected = df[df.int == 2]
          tm.assert_frame_equal(result, expected)
  
          result = store.select("df3", "int!=2")
          expected = df[df.int != 2]
          tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  from pandas._libs.tslibs import Timestamp
  import pandas
  from pandas import DataFrame, HDFStore, Index, MultiIndex, Series, _testing, bdate_range, concat, date_range, isna, read_hdf
  from pandas.tests.io.pytables.common import _maybe_remove, ensure_clean_store
  from pandas.io.pytables import Term
label_desc: Use image node_id 14 for calling a global function with example usage: test_string_select(setup_path) without return types