Not a huge post, but this has tripped me up several times, and sent me down some quite deep rabbit holes.

On to the story…

I once had a check to received calls like this:

var myData = Substitute.For<IData>();

...

myData
    .Add(Arg.Is<MyEntity>(a =>
        a.Active == true
        && a.Field1 == 1
        && a.Field2 == 42))
    .Received(1);

And I was getting the error:

NSubstitute extension methods like .Received()can only be called on objects created using Substitute.For()and related methods.

I was confident that I had declared it correctly, a few lines above… I could, in fact see that I had declared it correctly. As my brain slowly dribbled from my nose, I did a quick search on the web and found a solitary article that suggested I might have confused the Received and method calls; the correct syntax being:

myData
    .Received(1)
    .Add(Arg.Is<MyEntity>(a =>
        a.Active == true
        && a.Field1 == 1
        && a.Field2 == 42));

Hopefully, now that I’ve doubled the available resources available to people finding this error, it will plague me less in compensation.