How can I use NSubstitute with async methods?

How can I use NSubstitute with async methods?

You can use NSubstitute to create substitutes for async methods by returning a Task or Task<T>. For example, if you have an async method that returns a string, you can set up your substitute like this: mySubstitute.MyAsyncMethod().Returns(Task.FromResult("Hello"));.

What if my async method has parameters?

You can specify the parameters in the Returns method. For instance: mySubstitute.MyAsyncMethod(Arg.Any<int>()).Returns(Task.FromResult("Result")); This will return "Result" for any integer passed.

Can I throw exceptions from async methods?

Yes, you can throw exceptions from async methods in NSubstitute. Use Returns(Task.FromException<YourType>(new YourException())); to simulate an exception being thrown.

Are there any limitations I should be aware of?

One limitation is that NSubstitute does not support async void methods well, as they are not awaitable. It's best to use async Task methods.