Return a new object for each Returns() in NSubstitute

Question

I have created a substitute which mocks a web service interface for my unit testing which includes the following method definition:

public Message Invoke(Message input)

This method is called using:

var reply = webService.Invoke(messageObject)

When I make multiple calls to the same method, it is throwing the following exception:

System.InvalidOperationException : This message cannot support the operation because it has been read.

Here is my Nsubstitute mock code:

outputMessageObj = GetResponseMessage()
wsMock.Invoke(Arg.Any<Message>()).Returns(outputMessageObj)

How do I ensure that a new outputMessage object is returned each time the call is made?

Answer 1

Got it, just use a lambda to invoke a method which returns a new Message object each time:

wsMock.Invoke(Arg.Any<Message>()).Returns(x => GetResponseMessage())