docstr: Check results for a single column.
docstr_tok: ["Check","results","for","a","single","column","."]
code: def check_next_value_results(self, column, results, dates):
      """
      Check results for a single column.
      """
      self.assert_result_contains_all_sids(results)
  
      events = self.raw_events_no_nulls
      # Remove timezone info from trading days, since the outputs
      # from pandas won't be tz_localized.
      dates = dates.tz_localize(None)
      for asset, asset_result in results.iteritems():
          relevant_events = events[events.sid == asset.sid]
          self.assertEqual(len(relevant_events), 2)
  
          v1, v2 = relevant_events[self.next_value_columns[column]]
          e1, e2 = relevant_events["event_date"]
          t1, t2 = relevant_events["timestamp"]
  
          for date, computed_value in zip(dates, asset_result):
              if t1 <= date <= e1:
                  # If we've seen event 2, it should win even if we've seen
                  # event 1, because events are sorted by event_date.
                  self.assertEqual(computed_value, v1)
              elif t2 <= date <= e2:
                  # If we've seen event 1 but not event 2, event 1 should
                  # win.
                  self.assertEqual(computed_value, v2)
              else:
                  # If we haven't seen either event, then we should have
                  # column.missing_value.
                  assert_equal(
                      computed_value,
                      column.missing_value,
                      # Coerce from Timestamp to datetime64.
                      allow_datetime_coercions=True,
                  )
  
imports: from datetime import time
  from itertools import product
  from unittest import skipIf
  import blaze
  import numpy
  import pandas
  import pytz
  from zipline.pipeline import Pipeline, SimplePipelineEngine
  from zipline.pipeline.common import EVENT_DATE_FIELD_NAME, TS_FIELD_NAME, SID_FIELD_NAME
  from zipline.pipeline.data import DataSet, Column
  from zipline.pipeline.domain import US_EQUITIES, EquitySessionDomain
  from zipline.pipeline.loaders.events import EventsLoader
  from zipline.pipeline.loaders.blaze.events import BlazeEventsLoader
  from zipline.pipeline.loaders.utils import next_event_indexer, previous_event_indexer
  from zipline.testing import ZiplineTestCase
  from zipline.testing.fixtures import WithAssetFinder, WithTradingSessions
  from zipline.testing.predicates import assert_equal
  from zipline.utils.numpy_utils import categorical_dtype, datetime64ns_dtype, float64_dtype, int64_dtype
  from zipline.utils.pandas_utils import new_pandas, skip_pipeline_new_pandas
label_desc: Use image node_id 7 for calling the EventsLoaderTestCase obj's underlying member method code with example usage: obj.check_next_value_results(column, results, dates) without return types