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Unit test IObservable <T> with ObserveOnDispatcher

I need to check the code snippet

        var watcher = new FakeIFileSystemWatcher();
        watcher.FilesToBeImported
            .ObserveOnDispatcher()
            .Subscribe(list.Add);

so I created this little unit test, but I cannot get it to list the reasons. Count is always 0

    [Test]
    public void Foo()
    {
        var list = new List<string>();

        var watcher = new FakeIFileSystemWatcher();
        watcher.FilesToBeImported
            .ObserveOnDispatcher()
            .Subscribe(list.Add);

        Task task = Task.Factory.StartNew(() =>
        {                
            watcher.AddFile("cc");
            watcher.AddFile("cc");
            watcher.AddFile("cc");
        }, TaskCreationOptions.LongRunning);
        Task.WaitAll(task);

        Assert.AreEqual(3, list.Count);
    }

if I comment on the method

            .ObserveOnDispatcher()

it passes, but how can I make it work also with ObserveOnDispatcher ()?

+5
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3 answers

I decided to use the DispatcherUtil class that I found here Using WPF Manager in Unit Tests

now my code is next

    [Test]
    public void Foo()
    {
        var list = new List<string>();

        var watcher = new FakeIFileSystemWatcher();
        watcher.FilesToBeImported
            .ObserveOnDispatcher()
            .Subscribe(list.Add);

        Task task = Task.Factory.StartNew(() =>
        {
            watcher.AddFile("cc");
            watcher.AddFile("cc");
            watcher.AddFile("cc");
            watcher.AddFile("cc");
        }, TaskCreationOptions.LongRunning);
        Task.WaitAll(task);
        DispatcherUtil.DoEvents();
        Assert.AreEqual(4, list.Count);
    }

and it works like a charm

+1
source

ObserveOnDispatcher, "", , . unit test, ObserveOn, , . Scheduler.Immediate, DispatcherScheduler.Instance. , TestScheduler, .

+5

You can try calling your method as follows:

var dispatcher = Application.Current != null ? Application.Current.Dispatcher : Dispatcher.CurrentDispatcher;

 dispatcher.Invoke((Action)(() => YourMethodToTest());
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