public void SaveTest()
{
Shape createdObj = null;
var c = new CompositeShape();
_mockFileIO.Setup(x => x.SaveShape(It.IsAny <Stream>(), It.IsAny <Shape>()))
.Callback <Stream, Shape>((i, x) => { createdObj = x; });
c._fileWriter = _mockFileIO.Object;
c.Save(_mockFileStream.Object);
Assert.AreEqual(c, createdObj);
_mockFileIO.Verify(x => x.SaveShape(It.IsAny <Stream>(),
It.IsAny <Shape>()), Times.Once);
}