Unable to return value from another substitute

[psmolinsky]

When I configure a substitute to return a value which is obtained from another substitute, it does not work. For example:

public interface IFoo
{
   string Name { get; }
}

var foo1 = Substitute.For<IFoo>();
var foo2 = Substitute.For<IFoo>();

foo1.Name.Returns("Foobar");
foo2.Name.Returns(foo1.Name);

Console.WriteLine("Foo1: '{0}'", foo1.Name);
Console.WriteLine("Foo2: '{0}'", foo2.Name);

Output is:

Foo1: 'Foobar'
Foo2: ''

However slightly different setup works, but looks very weird:

foo1.Name.Returns("Foobar");
var name = foo1.Name;
foo2.Name.Returns(name);

[alexandrnikitin]

Hi Peter. Thanks for the issue. We have a similar one with properties #56. That happens because Returns is an extension method and it applies its value to the last call. Something like this happens:

arg1 = call foo2.Name
arg2 = call foo1.Name // the last call is to foo1
call Returns(arg1, arg2)

[dtchepak]

Hi @psmolinsky,

You could also try this:

foo1.Name.Returns("Foobar");
foo2.Name.Returns(x => foo1.Name);

The lambda function defers the call so the problem @alexandrnikitin mentioned doesn't occur. (This can cause other problems later; another call to foo2.Name.Returns(...) will end up setting foo1.Name I think, but often you can get away with it without problems.)

Or if the value of foo1.Name is not going to change, a clearer alternative to your second code snippet is:

var name = "Foobar";
foo1.Name.Returns(name);
foo2.Name.Returns(name);

[psmolinsky]

Hi guys, thanks for suggestions and explanation. It's definitely good enough for me. Although I think it would be nice to fix it.

[dtchepak]

Closing as part of a general cleanup of issues. Please re-open if any action is required.