text: import pytest
  from pyregions import standard_definition
  
  @pytest.fixture
  def default_required_columns()->standard_definition.RequiredColumns:
  	return standard_definition.RequiredColumns()
  
  def test_required_columns_using_default_values(default_required_columns):
  	default_columns = [
  		'regionCode', 'regionName', 'seriesCode', 'seriesName', 'seriesNotes', 'seriesScale', 'seriesUnits', 'seriesDescription', 'seriesTags'
  	]
  	# Should Be []
  	assert not default_required_columns.find_missing_columns(default_columns)
  
  	default_columns_with_extra = default_columns + ['extraColumn1', 'extraColumn2']
  
  	# Should be []
  	assert not default_required_columns.find_missing_columns(default_columns_with_extra)
  
  	with pytest.raises(ValueError):
  		default_required_columns.find_missing_columns(default_columns[1:] + ['extra1', 'extra2'])
  
  	# Now test if the optional 'tags' column throws an error if it is missing.
  	assert not default_required_columns.find_missing_columns(default_columns[:-1] + ['extra1', 'extra2'])
  
  def test_required_columns_using_custom_column_names(default_required_columns):
  	default_required_columns.region_name_column = 'region'
  	default_required_columns.note_column = 'notes'
  
  	correct_columns = [
  		'regionCode', 'region', 'seriesCode', 'seriesName', 'notes', 'seriesScale', 'seriesUnits', 'seriesDescription', 'seriesTags'
  	]
  
  	assert not default_required_columns.find_missing_columns(correct_columns)
  
  	wrong_columns = [
  		'regionCode', 'regionName', 'seriesCode', 'seriesName', 'seriesNotes', 'seriesScale', 'seriesUnits', 'seriesDescription', 'seriesTags'
  	]
  
  	with pytest.raises(ValueError):
  		default_required_columns.find_missing_columns(wrong_columns)