C#模拟一个带有内部属性设置器的类 [英] C# Mock a Class With an Internal Property Setter
问题描述
我正在尝试建立单元测试. Position类是在第三方库中实现的.但是对于我的单元测试,我需要将Size属性设置为特定值.
I am trying to build a unit test. The class Position is implemented in a third party library. But for my unit test I need the Size property to be set to a specific value.
public class Position
{
private double _size;
private double Size
{
get
{
return _size;
}
internal set
{
_size = value;
}
}
}
I read this post: How do you create a unit-testing stub for an interface containing a read-only member? but could not figure out how to make it work for me.
这是被测试的类(只是一个简化的示例). CalcPositionMetric()
方法中的pos
参数必须为Position
类型:
This is the class under test (just a simplified example). The pos
argument in the CalcPositionMetric()
method must be of type Position
:
public class PositionMetrics
{
public PositionMetrics()
{}
public double CalcPositionMetric(Position pos)
{
return 2 * pos.Size;
}
}
这是我的单元测试的一部分:
Here is a piece of my unit test:
using NUnit.Framework;
using NMock;
[TestFixture]
public class PositionUnitTests
{
[Test]
public void TestPosition()
{
Mock<Position> tmpPosMock = mFactory.CreateMock<Position>();
tmpPosMock.Expects.One.GetProperty(v => v.Size).WillReturn(7); /* !!! Exception !!! System.ArgumentException : mock object position has a getter for property Size, but it is not virtual or abstract */
/* Execute Test with tmpPositions*/
PositionMetrics pm = new PositionMetrics();
double result = pm.CalcPositionMetric(tmpPosMock.MockObject)
Assert.AreEqual(14, result);
}
}
但是正如您所看到的,我得到了一个例外.有人可以帮我解决这个问题吗?也欢迎任何其他解决方案!
But as you can see I get an exception. Could somebody help me to resolve this problem? Any other solutions are also welcome!
欢呼 康斯坦丁
推荐答案
已更新问题的新答案我建议您为此引入某种代理接口.请参见下面的代码:
New answer for the updated question I suggest you to introduce some kind of a proxy interface for that. See the code below:
interface IPosition {
int Size { get; }
}
class Position { //in 3rd party lib
public int Size {
get { return 5; }
}
}
class RealPosition : IPosition { //use this as your real object instead of using Position directly
private Position position;
public RealPosition(Position position) {
this.position = position;
}
public int Size {
get { return position.Size; }
}
}
class MockPosition : IPosition { //use this for testing
public int Size{ get; set; }
}
public class Program {
static void Main(string[] args) {
var pos = new MockPosition { Size = 7 };
Console.WriteLine(Calc(pos)); //prints 14
Console.ReadLine();
}
static int Calc(IPosition pos) { //change your method signature to work with interface
return pos.Size * 2;
}
}
旧答案.如果该类不是sealed
,则不需要任何模拟库.只需对所需的属性使用new
修饰符,如下所示:
Old answer If the class is not sealed
you don't need any mocking libraries. Just use the new
modifier for the required properties like this:
class Position {
public int Size { get { return 5; } }
}
class MockPosition : Position {
public new int Size { get; set; }
}
....
var mock= new MockPosition();
mock.Size = 7;
要在某种列表中使用这些项目,您必须像这样对它们进行投射:
To use these items in some sort of list you'll have to cast them like this:
var items = new List<Position>();
for (int i = 0; i < 5; i++) {
items.Add(new MockPosition { Size = i });
}
foreach (var item in items.Cast<MockPosition>()) {
Console.Write("{0}\t", item.Size); //prints 0 1 2 3 4
}
如果它是密封的并且该属性不是虚拟的,那么您将不得不使用其他一些技术,Moq
(我想您正在使用)不允许这样做
If it is sealed and the property is not virtual than you'll have to use some other techniques, Moq
(which I guess you are using) does not allow that
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