         element.getBoundingClientRect().width
 
       # assert the pane's flex scale. arguments is list of pane-scale pair
-      expectFlexScale = ->
-        args = Array::slice.apply(arguments, 0)
+      expectPaneScale = ->
+        args = Array::slice.call(arguments, 0)
         for paneScale in args
           expect(paneScale[0].getFlexScale()).toBeCloseTo(paneScale[1], 0.1)
 


      # test removeChild
      paneAxis.removeChild(models[2])
      expectResizeElement(i) for i in [1, 3]

  describe "when user drag the resize element", ->
    [container, containerElement] = []
    [resizeElementMove, getElementWidth, expectFlexScale] = []

    beforeEach ->
      container = new PaneContainer

      leftPane = container.getActivePane()
      middlePane = leftPane.splitRight()

      [resizeElements, paneElements] = []
      reloadElements = ->
        resizeElements = containerElement.querySelectorAll('atom-pane-resize-handle')
        paneElements = containerElement.querySelectorAll('atom-pane')
      reloadElements()
      expect(resizeElements.length).toBe(1)

      resizeElementMove(resizeElements[0], getElementWidth(paneElements[0]) / 2)
      expectPaneScale [leftPane, 0.5], [middlePane, 1.5]

      # add a new pane
      rightPane = middlePane.splitRight()
      reloadElements()
      clientX = getElementWidth(paneElements[0]) + getElementWidth(paneElements[1]) / 2
      resizeElementMove(resizeElements[1], clientX)
      expectPaneScale [leftPane, 0.5], [middlePane, 0.75], [rightPane, 1.75]
