我在结合 dotMemory、xUnit 和 async 时做错了什么吗

Question

我有一个单元测试，我试图验证我已经处理了曾经附加到主用户界面的文档。单元测试必须是异步的，因为一切都需要运行在 STA 线程下，我必须等待正在创建的用户界面。

我有一个助手可以将操作分派到 STA 线程。

我在测试主体中创建了 memory 对象，然后将其传递给异步方法，如下所示。

查看用 ### 注释的代码行以查看实际问题行。 dotMemory 报告该对象尚不存在，但我已经断言证明该对象确实存在。

（STA 助手类可以在 https://gist.github.com/bradphelan/cb4f484fbf6a7f9829de0dd52036fd63 找到）

这是与 async 和 dotMemory 相关的问题吗？

    [Collection("Memory leaks")]
public class MemLeakSpec
{
    public MemLeakSpec(ITestOutputHelper output)
    {
        DotMemoryUnitTestOutput.SetOutputMethod(output.WriteLine);
    }

    [Fact]
    [DotMemoryUnit(FailIfRunWithoutSupport = true)]
    public void ShouldCollectProjectX()
    {
        dotMemory.Check (memory => { STAThread.Run(() => ShouldCollectProjectAsyncX(memory)).Wait(); });
    }

    class Document { }

    class Container { public Document Document; };

    Document CreateFoo() => new Document();

    private async Task ShouldCollectProjectAsyncX(Memory memory)
    {
        await Task.Delay(TimeSpan.FromMilliseconds(50));

        Container container = new Container();

        memory.GetObjects(@where => @where.Type.Is<Document>())
                         .ObjectsCount.Should()
                         .Be(0);

        Document documentA = CreateFoo();
        container.Document = documentA;

        // Verify with dotMemory that the object exists.
        // ### This fails even though I have verified
        // ### the document exists
        memory.GetObjects(@where => @where.Type.Is<Document>())
                         .ObjectsCount.Should()
                         .Be(1);

        // Open a new project which should dispose the old one and thus
        // remove any reference to GenericWeinCadFolder
        container.Document = null;

        memory.GetObjects(@where => @where.Type.Is<Document>())
                         .ObjectsCount.Should()
                         .Be(0);


        GC.KeepAlive(container);
    }
}

我已经创建了上述相同测试的同步版本并且没有失败。下面有两个测试 ShouldCollectAsync 和 ShouldCollectSync。 async 失败，sync 通过。

[Collection("Memory leaks")]
public class MemLeakSpec
{
    public MemLeakSpec(ITestOutputHelper output)
    {
        DotMemoryUnitTestOutput.SetOutputMethod(output.WriteLine);
    }

    [Fact]
    [DotMemoryUnit(FailIfRunWithoutSupport = true)]
    public void ShouldCollectAsync()
    {
        dotMemory.Check (memory => { STAThread.Run(() => ShouldCollectProjectAsyncX(memory)).Wait(); });
    }

    /// This test is almost identical to the ShouldCollectAsync
    /// but it passes
    [Fact]
    [DotMemoryUnit(FailIfRunWithoutSupport = true)]
    public void ShouldCollectSync ()
    {
        dotMemory.Check (memory => { STAThread.Run(() => ShouldCollectProjectSync(memory)); });
    }

    class Document { }

    class Container { public Document Document; };

    Document CreateFoo() => new Document();

    private async Task ShouldCollectProjectSync(Memory memory)
    {
        Container container = new Container();

        memory.GetObjects(@where => @where.Type.Is<Document>())
                         .ObjectsCount.Should()
                         .Be(0);

        Document documentA = CreateFoo();
        container.Document = documentA;

        // Verify with dotMemory that the object exists.
        // #### Passes here
        memory.GetObjects(@where => @where.Type.Is<Document>())
                         .ObjectsCount.Should()
                         .Be(1);

        GC.KeepAlive(documentA);
        GC.KeepAlive(container);
    }
    private async Task ShouldCollectProjectAsyncX(Memory memory)
    {

        await Task.Delay(TimeSpan.FromMilliseconds(50));

        Container container = new Container();

        memory.GetObjects(@where => @where.Type.Is<Document>())
                         .ObjectsCount.Should()
                         .Be(0);

        Document documentA = CreateFoo();
        container.Document = documentA;

        // Verify with dotMemory that the object exists.
        // #### FAILS here
        memory.GetObjects(@where => @where.Type.Is<Document>())
                         .ObjectsCount.Should()
                         .Be(1);

        GC.KeepAlive(documentA);
        GC.KeepAlive(container);
    }
}

Answer 1

dotMemory Unit 要求其所有方法都应从 "test" 方法调用。想一想就像在开始时有一个电话 dotMemoryUnit.TestStart ShouldCollectAsync 和 dotMemoryUnit.TestEnd 完成。您没有公开 STAThread.Run 的实现，所以我无法提供更详细的建议，但想法是在异步例程完成时在测试方法中等待。

Answer 2

对我来说，将测试包装在本地函数中就足够了：

public void TestMethod()
{
    async Task LocalFunction()
    {
        // here you can make async calls
        await Task.Delay(...);
    }

    LocalFunction().ConfigureAwait(true).GetAwaiter().GetResult();
}

我在结合 dotMemory、xUnit 和 async 时做错了什么吗

Am I doing something wrong combining dotMemory, xUnit and async

c#

xunit

async-await

dotmemory