Unit testing ViewModel with ReactiveCommand

[powerdude]

Hi, I'm trying to test this view model and running into some issues. When the command executes, the test just times out. I'm new to reactive programming so there could be a problem with how I've set things up. Any help would be greatly appreciated.

using FluentAssertions;
using R3;
using System.Windows.Input;

public class Item
{
    public required string Text { get; set; }
}

public partial class SampleViewCommandModel
{
    public ObservableList<Item> Items { get; set; } = [
        new Item { Text = "Item 1" },
        new Item { Text = "Item 2" },
        new Item { Text = "Item 3" }
    ];

    public ValueTask RemoveItem(Item item)
    {
        _ = Items.Remove(item);
        return ValueTask.CompletedTask;
    }
}

public partial class BindableSampleViewCommandModel : INotifyPropertyChanged, IDisposable
{
    private readonly CompositeDisposable compositeDisposable=[];
    public BindableSampleViewCommandModel() : this(new SampleViewCommandModel())
    {

    }

    public BindableSampleViewCommandModel(SampleViewCommandModel model)
    {
        Model = model;
        Items ??= model.Items.ToNotifyCollectionChanged(
                SynchronizationContextCollectionEventDispatcher.Current
            );

        RemoveItem = new ReactiveCommand<Item>((x, ctx) => model.RemoveItem(x));

        if (model is INotifyPropertyChanged npc)
        {
            npc.PropertyChanged += Npc_PropertyChanged;
        }
    }

    private void Npc_PropertyChanged(object? sender, PropertyChangedEventArgs e) => OnPropertyChanged(e.PropertyName);

    private readonly BindableReactiveProperty<Item> item = new();
    public SampleViewCommandModel Model { get; private set; }
    public NotifyCollectionChangedSynchronizedViewList<Item> Items { get; private set; }
    public ReactiveCommand<Item> RemoveItem { get; private set; }

    /// <inheritdoc />
    public void Dispose() => this.compositeDisposable.Dispose();

    public event PropertyChangedEventHandler? PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

public class BindableSampleViewModelCommandTests
{
    [Fact]
    public void RemoveItem()
    {
        var vm = new BindableSampleViewCommandModel();
        using var monitoredVm = vm.Monitor();
        using var monitoredList = vm.Items.Monitor();

        _ = vm
            .Items.Should()
            .HaveCount(3);
         vm.RemoveItem.Execute(vm.Items[1]);
       
        _ = vm
            .Items.Should()
            .HaveCount(2);
           _ = monitoredList.Should().Raise("CollectionChanged");
              }
}

Also, is it possible for ReactiveCommand<T> and ReactiveCommand<TInput, TOutput> to take a Func<T,bool>, or an equivalent, for CanExecute so that it can check the input parameter to make sure it is valid before running the command? I see the command could be created from an IObservable<bool>, but it doesn't help if you have a UI like the following:

<custom:ParentView Source="{Binding Items}">
		<DataTemplate>
		  <ListView ItemsSource="{Binding Data}"
					Margin="0, 50, 0, 10">
			<ListView.ItemTemplate>
			  <DataTemplate>
				<StackPanel Orientation="Horizontal">
				  <TextBlock Text="{Binding Text}"
							 VerticalAlignment="Center" />

				  <Button Content="Delete"
						  Command="{utu:AncestorBinding AncestorType=custom:ParentView, Path=DataContext.RemoveItem}"
						  CommandParameter="{Binding}" />
				</StackPanel>
			  </DataTemplate>
			</ListView.ItemTemplate>
		  </ListView>
		</DataTemplate>
	</custom:ParentView>

the problem is the CommandParameter for the command. Not a real opportunity to create an observable without compromising the UI as far as I know.

[powerdude]

I think I sorted this out. Using AwaitOption.Drop worked.