@Test
public void screenToSeriesY_returnsSeriesValue() {

    when(xyPlot.getBounds()).thenReturn(new RectRegion(-100, 100, -100, 100));
    assertEquals(100, graphWidget.screenToSeriesY(new PointF(0, 0)).intValue());
    assertEquals(-100, graphWidget.screenToSeriesY(new PointF(100, 100)).intValue());
    assertEquals(0, graphWidget.screenToSeriesY(new PointF(50, 50)).intValue());
}