old_contents: from pyqode.qt import QtCore
  from pyqode.qt.QtTest import QTest
  from pyqode.core.api import TextHelper
  from pyqode.core import modes
  from test.helpers import editor_open
  
  
  def get_mode(editor):
      return editor.modes.get(modes.SmartBackSpaceMode)
  
  
  def test_enabled(editor):
      mode = get_mode(editor)
      assert mode.enabled
      mode.enabled = False
      mode.enabled = True
  
  
  @editor_open(__file__)
  def test_key_pressed(editor):
      QTest.qWait(1000)
      TextHelper(editor).goto_line(21, 4)
      QTest.qWait(2000)
      assert editor.textCursor().positionInBlock() == 4
      QTest.keyPress(editor, QtCore.Qt.Key_Backspace)
      QTest.qWait(2000)
      assert editor.textCursor().positionInBlock() == 0
      TextHelper(editor).goto_line(19, 5)
      QTest.qWait(2000)
      assert editor.textCursor().positionInBlock() == 5
      QTest.keyPress(editor, QtCore.Qt.Key_Backspace)
      QTest.qWait(2000)
      assert editor.textCursor().positionInBlock() == 4
  
      TextHelper(editor).goto_line(20, 0)
      QTest.qWait(2000)
      assert editor.textCursor().positionInBlock() == 0
      QTest.keyPress(editor, QtCore.Qt.Key_Backspace)
      QTest.qWait(2000)
      assert editor.textCursor().positionInBlock() == 28
  
new_contents: from pyqode.qt import QtCore
  from pyqode.qt.QtTest import QTest
  from pyqode.core.api import TextHelper
  from pyqode.core import modes
  from test.helpers import editor_open
  
  
  def get_mode(editor):
      return editor.modes.get(modes.SmartBackSpaceMode)
  
  
  def test_enabled(editor):
      mode = get_mode(editor)
      assert mode.enabled
      mode.enabled = False
      mode.enabled = True
  
  
  @editor_open(__file__)
  def test_key_pressed(editor):
      QTest.qWait(1000)
      TextHelper(editor).goto_line(21, 4)
      # QTest.qWait(2000)
      assert editor.textCursor().positionInBlock() == 4
      QTest.keyPress(editor, QtCore.Qt.Key_Backspace)
  
subject: Reduce test backspace, we just need to ensure it really eats tab_len spaces