Authentication path does not include the path Spree is mounted at

[lailsonbm]

When the Spree engine is mounted at a custom path (such as /store), the authentication path provided by spree_social (/users/auth/:provider by default) does not include this path.

This issue would be easy to solve by setting Spree::SocialConfig[:path_prefix] = 'store/users', but the problem is that the callback path (/users/auth/:provider/callback by default) does include the prefix, so when the :path_prefix is configured in this way, the actual callback route becomes /store/store/users/auth/facebook/callback.

As expected, this makes the callback chain to fail because the app asked the provider to redirect to /store/users/auth/facebook/callback. So, which behavior is correct?

Steps to reproduce the bug

1. Create a new spree app, as described in the Getting Started guide.
2. In the routes, change the path of the Spree engine to :at => '/store'.
3. Install spree_social as described in the README and create a authentication method in the Spree Admin (Facebook, for example).
4. Notice that the authentication URL is /users/auth/facebook, instead of /store/users/auth/facebook, as expected.
5. When this path is accessed, it redirects to /users/auth/facebook/callback, but the user gets an error, because this URL does not exists. It is in fact /store/users/auth/facebook/callback.

I'm currently investigating how to fix this. Please just confirm whether the expected behavior is to include the Spree engine path in all paths generated by the spree social.

[lailsonbm]

The issue seems to be related with Devise + Omniauth: https://github.com/plataformatec/devise/issues/2692

[gduquesnay]

seems related to #107

[radar]

Agreed, related to #107.