Null reference exception when using the "new" keyword with properties

[howcheng]

Several months ago, I reported #1175 and I think this may be related because it again involves subtyping with the use of the "new" keyword.

I have an interface (IRepository<T>) that defines a property (Foo Foo { get; set;}), and then a derived interface (IRepository<T, TK>) that redefines that property (Foo<T>). Next, I have a Service<T> class which takes a IRepository<T> in its constructor and sets its own Foo property from the repository property, then a derived Service<T, TK> class which takes a IRepository<T, TK> in its constructor and passes it to the base.

When creating a new instance of the Service<T, TK> class using a mocked IRepository<T, TK>, the Foo property is null, presumably the setter in the base class constructor uses the base interface's property definition, which is of type Foo and not Foo<T>.

Here is a fiddle that demonstrates the issue: https://dotnetfiddle.net/SDY3JZ

When using actual concrete classes, this all works fine, it's just the mock that has problems.

Thanks.

[howcheng]

I recently learned about the .As<>() method, so it turns out I was just doing the setup for the mock incorrectly.