Fix up the scoping for the @mock macro.

[kuszmaul]

Previously, the macro required Mocking to be visible in the caller's context: It was invoking Mocking.activated(), for exmaple. Now it invokes $activated(), which makes sure that the code uses the right version of activated. Similarly for get_alternate and Patch.

Also, the macro was doing some unceessary gensym calls, which macro hygene can take care of automatically.

[nickrobinson251]

Thanks, @kuszmaul! I think this LGTM, but i'll hold off merging for now to give other contributors here a chance to review (cc @omus @iamed2 @oxinabox @rofinn)

Also, this is a nice clean-up, but curious if there was an issue you ran into which prompted it? if so, is it something worth adding as a test case?

[kuszmaul]

Yes, I was doing some cleanup of the imports in some RAI code, which were something like:

Old:

import Mocking
...
   @mock something()

New:

using Mocking: @mock
...
  @mock something()

Partly because the RAI style guide says that's how we want to do things.

Since the module didn't otherwise using Mocking, I thought it would be fine. But it doesn't work with the current code., where I need to write

using Mocking: Mocking, @mock
...
  @mock something()

[oxinabox]

googe improvement, It would be possible to create a test for this but i do not think worth the effort