New cop to check for the use of Time.zone= method.

[olivierbuffon]

Is your feature request related to a problem? Please describe.

I've been through a code base lately that use to use Time.zone= to temporarily update the application time zone for a specific operation.
This might cause unexpected behaviors if the time zone is not set back to its original value.
Most of the time I've seen this pattern used in specs like:

before do
  Time.zone = 'EST'
end

Describe the solution you'd like

In order to avoid some issues related to the application time zone update, I would recommend the usage of Time.use_zone(time_zone, &block) instead. So we could be sure the time zone always reverts back to its initial value.
Its also really simple to use in specs using the around hook:

around(:example) do |example|
  Time.use_zone('EST') { example.call }
end

What do you think?

Describe alternatives you've considered

N/A

Additional context

N/A

[andyw8]

Setting Time.zone within the app's config is valid, so I suppose this cop should be restricted to test code?

[olivierbuffon]

@andyw8 Thanks for your feedback.
Well I think you're right! Since most of the time I've seen this in tests I agree this might be a better approach.
I'll update my code and open a PR 😃