@Test
public void drawMarkers_drawsLineForEachMarker() {

    xyPlot.addMarker(new XValueMarker(1, "x"));
    xyPlot.addMarker(new YValueMarker(-1, "y"));
    graphWidget.drawMarkers(canvas);
    // TODO: verifications
    verify(canvas, times(2))
            .drawLine(anyFloat(), anyFloat(), anyFloat(), anyFloat(), any(Paint.class));
}