text: ################################################################################
  #
  # Copyright (c) 2019, the Perspective Authors.
  #
  # This file is part of the Perspective library, distributed under the terms of
  # the Apache License 2.0.  The full license can be found in the LICENSE file.
  #
  
  import pandas as pd
  from mock import patch
  from perspective import PerspectiveWidget, Plugin, PerspectiveError
  
  
  class TestLayout:
  
      def test_layout_invalid_plugin(self):
          with patch('IPython.display.display'):
              df = pd.DataFrame([1, 2], columns=['1'])
              PerspectiveWidget(df, plugin=Plugin.YBAR)
              PerspectiveWidget(df, plugin='Y Line')
              try:
                  PerspectiveWidget(df, plugin='test')
                  assert False
              except PerspectiveError:
                  pass
  
              try:
                  PerspectiveWidget(df, plugin=5)
                  assert False
              except PerspectiveError:
                  pass
  
      def test_layout_invalid_columns(self):
          with patch('IPython.display.display'):
              df = pd.DataFrame([1, 2], columns=['1'])
              PerspectiveWidget(df, plugin=Plugin.YBAR, columns=['1'])
              try:
                  PerspectiveWidget(df, plugin=Plugin.YBAR, columns=5)
                  assert False
              except PerspectiveError:
                  pass
  