is Rails.cache purged between tests?

Question

We cache id/path mapping using Rails.cache in a Rails 3.2 app. On some machines it works OK, but on the others values are wrong. The cause is hard to track so I

Answer 1

A more efficient (and easier) method is to set the test environment's cache to use NullStore:

# config/environments/test.rb:
config.cache_store = :null_store

The NullStore ensures that nothing will ever be cached.

For instance in the code below, it will always fall through to the block and return the current time:

Rails.cache.fetch('time') { Time.now }

Also see the Rails Caching guide: http://guides.rubyonrails.org/caching_with_rails.html#activesupport-cache-nullstore

Answer 2

Add:

before(:all) do
  Rails.cache.clear
end

to have the cache cleared before each spec file is run.

Add:

before(:each) do
  Rails.cache.clear
end

to have the cache cleared before each spec.

You can put this inside spec/spec_helper.rb within the RSpec.configure block to have it applied globally (recommended over scattering it per spec file or case).

RSpec by default does not clear that cache automatically.