The provider for the source IQueryable doesn't implement IAsyncQueryProvider

Question

I have some codes like below, I want to write unit tests my method. But I\'m stuck in async methods. Can you help me please ?

public class Panel
{
    publi         


        

Answer 1

You could implement an AsyncEnumerable which can be used like this:

private readonly IQueryable panels = new AsyncEnumerable(new List() 
{
    panel
});

---

Here is the implementation of it:

public class AsyncEnumerable : EnumerableQuery, IAsyncEnumerable, IQueryable
{
    public AsyncEnumerable(IEnumerable enumerable) : base(enumerable) { }

    public AsyncEnumerable(Expression expression) : base(expression) { }

    public IAsyncEnumerator GetEnumerator()
    {
        return new AsyncEnumerator(this.AsEnumerable().GetEnumerator());
    }

    IQueryProvider IQueryable.Provider => new AsyncQueryProvider(this);
}

The AsyncEnumerator class:

public class AsyncEnumerator : IAsyncEnumerator
{
    private readonly IEnumerator _inner;

    public AsyncEnumerator(IEnumerator inner)
    {
        _inner = inner;
    }

    public void Dispose()
    {
        _inner.Dispose();
    }

    public T Current => _inner.Current;

    public Task MoveNext(CancellationToken cancellationToken)
    {
        return Task.FromResult(_inner.MoveNext());
    }
}

The AsyncQueryProvider class:

public class AsyncQueryProvider : IAsyncQueryProvider
{
    private readonly IQueryProvider _inner;

    internal AsyncQueryProvider(IQueryProvider inner)
    {
        _inner = inner;
    }

    public IQueryable CreateQuery(Expression expression)
    {
        return new AsyncEnumerable(expression);
    }

    public IQueryable CreateQuery(Expression expression)
    {
        return new AsyncEnumerable(expression);
    }

    public object Execute(Expression expression)
    {
        return _inner.Execute(expression);
    }

    public TResult Execute(Expression expression)
    {
        return _inner.Execute(expression);
    }

    public IAsyncEnumerable ExecuteAsync(Expression expression)
    {
        return new AsyncEnumerable(expression);
    }

    public Task ExecuteAsync(Expression expression, CancellationToken cancellationToken)
    {
        return Task.FromResult(Execute(expression));
    }
}