public void SaveTest()
{
Shape createdObj = null;
var triangle = new Triangle(
new Point(0, 0),
new Point(3, 0),
new Point(0, 3));
_mockFileIO.Setup(x => x.SaveShape(It.IsAny <Stream>(), It.IsAny <Shape>()))
.Callback <Stream, Shape>((i, x) => { createdObj = x; });
triangle._fileWriter = _mockFileIO.Object;
triangle.Save(_mockFileStream.Object);
Assert.AreEqual(triangle, createdObj);
_mockFileIO.Verify(x => x.SaveShape(It.IsAny <Stream>(),
It.IsAny <Shape>()), Times.Once);
}