Ensure belongs_to finder method sends a non-nil key

[jassa]

Hey there,
I found the following weird behavior:

Let's say a Post belongs_to a User, and there is a post without a user_id

post = Post.first # post without user_id
post.user.try(:name)
ActiveResource::ResourceNotFound: Failed.  Response code = 404.  Response message = Not Found .

On my logs I see it tried to get users/.xml

18:49:59 web.1 | Started GET "/api/users/.xml" for 127.0.0.1 at 2013-04-25 18:49:59 -0500
18:49:59 web.1 | ActionController::RoutingError (No route matches [GET] "/api/users/.xml"):

This PR fixes this, and returns nil instead:

post.user.try(:name)
=> nil

What do you think?

Additionally you might want to raise an ArgumentError when doing Post.find nil (same thing happens)

[tamird]

👍

[sikachu]

Would you mind adding a test for this?

[jassa]

Ok, I added a couple of tests