NSubstitute Received() throws System.NullReferenceException on Grpc mocked call

[JosimarTT]

NSubstitute Received() throws System.NullReferenceException on Grpc mocked call

[Ergamon]

The problem is the await of the result from the Received call.

Basically this is how NSubstitute works. The Received method call is to check, if the right action has happened. It is more or less a side effect that it also returns something.

The result is generated by the NSubstitute rules. If it has a parameterless constructor, it is generated. If it requires parameters, it returns null.

So the test passes and works as expected, but after your assertion you await a Task. But this task instance is null.

Just remove the await and everything works you want.

Sadly a lot of analyzers spot the missing await and tell you that it is needed. But sadly the contrary is the case.

[dtchepak]

Hi @JosimarTT ,

This seems similar to #722 ? Would you be able to post a minimal repro I can run?

[JosimarTT]

@dtchepak I updated my post with an example repo