遺留代碼以某種方式對ThreadAbortException作出反應的單元測試

Question

我有一些遺留代碼，我想要進行測試。 這是必需品的復制品：

public class LegacyUnit
{
    private readonly ICollaborator collaborator;

    public LegacyUnit(ICollaborator collaborator) 
    {
        this.collaborator = collaborator;
    }

    public object GetStuff(HttpContextBase context, string input)
    {
        try 
        {
            if (input == "")
            {
                context.Response.End();
            }

            collaborator.DoOtherStuff();

            return "Done!";
        }
        catch (ThreadAbortException) 
        { }

        return null;
    }
}

現在，這個遺留單元存在一些問題，但是現在我只是試圖讓它受到考驗。 具體來說，我想測試一下，如果Response.End()引發一個ThreadAbort ，則不會調用該collaborator.DoOtherStuff 。

問題：你如何提出這樣的例外？

我已經閱讀了這個問題及其在ThreadAbortException答案 ，並了解它是特殊的。 但是，我從這些帖子中看不到如何在單元測試中處理這個問題。

這是我的嘗試：

[Test]
public void DoesNotCallCollaboratorOnThreadAbort()
{
    var testResponseMock = new Mock<HttpResponseBase>();
    var testContextMock = new Mock<HttpContextBase>();
    var collaboratorMock = new Mock<ICollaborator>();

    testContextMock.Setup(x => x.Response).Returns(testResponseMock.Object);
    testResponseMock.Setup(x => x.End()).Throws<ThreadAbortException>(); // Compile error

    var unit = new LegacyUnit(collaboratorMock.Object);
    unit.GetStuff(testContextMock.Object, "");

    collaboratorMock.Verify(c => c.DoOtherStuff(), Times.Never);
}

顯然編譯器抱怨： ThreadAbortException沒有可用的構造函數。 此外，它是sealed （可能有充分的理由），因此創建一個“可測試的”子類是行不通的。

獲得此類代碼的正確方法是什么？ 它甚至是可行的，還是LegacyUnit對測試不友好？

---

完整，最小的repro（帶有NUnit 2.6.4和Moq 4.5.9的空.NET 4.5類庫）：

public interface ICollaborator
{
    void DoOtherStuff();
}

public class LegacyUnit
{
    private readonly ICollaborator collaborator;

    public LegacyUnit(ICollaborator collaborator)
    {
        this.collaborator = collaborator;
    }

    public object GetStuff(HttpContextBase context, string input)
    {
        try
        {
            if (input == "") context.Response.End();
            collaborator.DoOtherStuff();
            return "Done!";
        }
        catch (ThreadAbortException)
        { }

        return null;
    }
}

[TestFixture]
public class LegacyUnitTests
{
    [Test]
    public void DoesNotCallCollaboratorOnThreadAbort()
    {
        var testResponseMock = new Mock<HttpResponseBase>();
        var testContextMock = new Mock<HttpContextBase>();
        var collaboratorMock = new Mock<ICollaborator>();

        testContextMock.Setup(x => x.Response).Returns(testResponseMock.Object);
        testResponseMock.Setup(x => x.End()).Throws<ThreadAbortException>(); // Compile error here

        var unit = new LegacyUnit(collaboratorMock.Object);
        unit.GetStuff(testContextMock.Object, "");

        collaboratorMock.Verify(c => c.DoOtherStuff(), Times.Never);
    }
}

Answer 1

通過在其上調用Abort在目標線程中引發ThreadAbortException 。 您可以創建一個線程來運行測試，並在模擬testResponseMock.End調用Abort ，例如

testContextMock.Setup(x => x.Response).Returns(testResponseMock.Object);

var unit = new LegacyUnit(collaboratorMock.Object);
var thread = new Thread(() => unit.GetStuff(testContextMock.Object, ""));

testResponseMock.Setup(x => x.End()).Callback(() => { Thread.CurrentThread.Abort(); });

thread.Start();
thread.Join();

collaboratorMock.Verify(c => c.DoOtherStuff(), Times.Never);