IsAwaitable 1.0.1

How to use

// The extension is defined within this namespace
// in order to be readily available
using System.Threading.Tasks;

// On instances
var promise = GetSomethingAsync();
_ = promise.IsAwaitable(); // true

// On types
_ = typeof(Task).IsAwaitable(); // true

// On value tasks
_ = typeof(ValueTask).IsAwaitable(); // true
_ = typeof(ValueTask<>).IsAwaitable(); // true

// On custom awaitables!
class CustomDelay
{
    private readonly TimeSpan _delay;

    public CustomDelay(TimeSpan delay) =>
        _delay = delay;

    public TaskAwaiter GetAwaiter() =>
        Task.Delay(_delay).GetAwaiter();
}

var delay = new CustomDelay(TimeSpan.FromSeconds(2));
_ = delay.IsAwaitable(); // true
await delay;

Use with dynamic await

async Task<object> AwaitResultOrReturn(object instance)
{
    return instance.IsAwaitable()
        ? await (dynamic)instance // magic
        : instance;
}

var foo = GetFoo();
var fooTask = Task.FromResult(foo);

var result1 = await AwaitResultOrReturn(foo);
var result2 = await AwaitResultOrReturn(fooTask);

// foo == result1 == result2