遗留代码以某种方式对 ThreadAbortException 做出反应的单元测试

Question

我有一些现有的遗留代码，我想对其进行测试。这是要点的复制品：

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;
    }
}

现在，这个遗留单元有一些问题，但现在我只是想对其进行测试。具体来说，我想测试 collaborator.DoOtherStuff 是 而不是 如果 Response.End() 引发 ThreadAbort.

问题：如何引发这样的异常？

我已通读this question and its answers on ThreadAbortException，明白它的特别之处。但是，我没有从这些帖子中看到如何在单元测试中处理这个问题。

这是我的尝试：

[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);
}

显然编译器会抱怨：ThreadAbortException 没有可用的构造函数。此外，它是 sealed（可能有充分的理由），因此创建 "testable" sub-class 将不起作用。

获取此类待测代码的正确方法是什么？它是否可行，或者 LegacyUnit 是否太不适合测试？

完整的最小重现（带有 NUnit 2.6.4 和 Moq 4.5.9 的空 .NET 4.5 class 库）：

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

ThreadAbortException 通过调用 Abort 在目标线程中引发。您可以创建一个线程来运行测试并在 testResponseMock.End 的模拟中调用 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);

遗留代码以某种方式对 ThreadAbortException 做出反应的单元测试

Unit test that legacy code reacts to ThreadAbortException in a certain way

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