Add ability to force alternative on dashboard

[ccallebs]

From #427 -- This simply allows selecting the current users variation/alternative on the dashboard. Helpful for when you're debugging a single alternative and don't want to keep overriding the URL parameter.

Example:

Note: Not happy with the copy, but it's late and I couldn't think of anything else. :)

[coveralls]

Coverage decreased (-0.1%) to 98.978% when pulling 77a984a on ccallebs:add-force-alternative into 95cff59 on splitrb:master.

[andrew]

Looks handy, just need to fix the failing test and I'll get it merged, thanks!

[dmur]

👍

[ccallebs]

@andrew Spec fixed, branch rebased into single commit! Sorry for the delay.

[andrew]

@ccallebs thanks, merged! 🎉

[teguhn]

Does this mean we can't use the URL parameter anymore?

[ccallebs]

@teguhn The URL parameters should still overwrite whatever value the user has set. This just allows you to overwrite globally, so you don't have to keep adding the URL parameter when testing.

[gibacache]

@ccallebs I get undefined method 'current_user' for #<Split::Dashboard:0x00557c18105470> when trying to force for current_user.
I have the RedisAdapter for persistance:
config.persistence = Split::Persistence::RedisAdapter.with_config(lookup_by: -> (context) { context.send(:current_user).try(:id) })
How can I have the current_user method available in the Dashboard? Am I doing something wrong?
Thanks!

[ccallebs]

@gibacache I'm unfamiliar with that syntax, but you might try evaluating what methods are available from context. For example, if you can access cookies/session you could derive the current_user.