code: def test_single_block_df_with_horizontal_axis(self):
      # GH 47713
      df = DataFrame(
          {
              "col1": [5, 0, np.nan, 10, np.nan],
              "col2": [7, np.nan, np.nan, 5, 3],
              "col3": [12, np.nan, 1, 2, 0],
              "col4": [np.nan, 1, 1, np.nan, 18],
          }
      )
      result = df.fillna(50, limit=1, axis=1)
      expected = DataFrame(
          [
              [5.0, 7.0, 12.0, 50.0],
              [0.0, 50.0, np.nan, 1.0],
              [50.0, np.nan, 1.0, 1.0],
              [10.0, 5.0, 2.0, 50.0],
              [50.0, 3.0, 0.0, 18.0],
          ],
          columns=["col1", "col2", "col3", "col4"],
      )
      tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  from pandas._config import using_pyarrow_string_dtype
  from pandas import Categorical, DataFrame, DatetimeIndex, NaT, PeriodIndex, Series, TimedeltaIndex, Timestamp, date_range, to_datetime
  import pandas._testing
  from pandas.tests.frame.common import _check_mixed_float
label_desc: Use image node_id 41 for calling the TestFillNA obj's underlying member method code with example usage: obj.test_single_block_df_with_horizontal_axis() without return types