def METHOD_NAME(self):
    """
    Test that a legend created with no data produces warning.
    """
    # Enable legends
    self.plot()
    self._control.Legend.setCheckState(QtCore.Qt.Checked)
    self._control.Legend.clicked.emit(True)
    self._control.Legend2.setCheckState(QtCore.Qt.Checked)
    self._control.Legend2.clicked.emit(True)
    # Remove lines
    select = self._widget.currentWidget().PostprocessorSelectPlugin
    var = 'air_temp_set_1'
    select._groups[0]._toggles[var].CheckBox.setCheckState(QtCore.Qt.Unchecked)
    select._groups[0]._toggles[var].CheckBox.clicked.emit(False)
    var = 'snow_depth_set_1'
    select._groups[0]._toggles[var].CheckBox.setCheckState(QtCore.Qt.Unchecked)
    select._groups[0]._toggles[var].PlotAxis.setCurrentIndex(1)
    select._groups[0]._toggles[var].CheckBox.clicked.emit(False)
    self.assertImage('testEmpty.png')