FrenkyB FrenkyB - 3 months ago 18
C# Question

Mocking inner objects gets lost with function call

I am mocking chessboard, on which I can add pieces. I want to unit test allowed LinearMoves, when there are some pieces on the chessboard.

Code starts with:

Chessboard.Setup(x => x.GetPiece(C1.Object)).Returns(Piece_C1.Object);
Chessboard.Setup(x => x.GetPiece(A3.Object)).Returns(Piece_A3.Object);

As you can see I first setup chessboard and both pieces on this chessboard. I also mock GetPiece(IPosition) function, which should return IPiece.

If I try with debugger GetPiece(IPosition pos) function at the end of code above, everything is OK, piece is returned:

enter image description here

Now I create new object LinearMoves, where I pass chessboard as parameter:

linearMoves = new LinearMoves(Chessboard.Object, Piece_A1.Object);

When GetPiece with same position gets called in this new object, it returs null:

IPiece currentPiece = chessboard.GetPiece(currentPosition);

Basically like Piece_C1 and Piece_A3 were never added. Where are they lost? It seems like Chessboard created and Chessboard passed as parameter into constructor are not the same objects.


I've found out that this search with mocked object Mock returns correct result, search with IPosition doesn't return anything.

  1. Search with
    returns correct result:

enter image description here

  1. Search with
    (but coordinates are the same) doesn't return anything:

enter image description here


The problem is that Position is a reference type,so two objects are equal only if they point to the same object.

You need to help your setup method compare Positions

chessboard.Setup(x => x.GetPiece(It.Is< Position>(k => k.X== "A" && K.Y ==3))).Returns(...);