Caching in Rails by Default

dubstep · July 3, 2011, 8:14am

So, maybe I need to go to the rails list with this, but I hit my error
while
testing so I figured I’d ask here first.

Basically, Rails.cache.fetch is being persisted by default in my rails
project between rspec runs. I’ve illustrated what I’m observing here:

Furthermore, if you run that once, and then take out the test that
doesn’t
raise the error, its still in the cache.

So, to get at the ‘issue’ I’m describing specifically. If you first run
‘rspec spec/controllers/application_controller_spec.rb’ with the
following:

github.com

softwaregravy/rspec-troubleshoot/blob/0e22ce887cde602e49dc9bf7fa25406882b038f0/spec/controllers/application_controller_spec.rb


require 'spec_helper'

describe ApplicationController do 
  describe "#redirect_to_candies" do 
    controller do 
      before_filter :redirect_to_candies 
      def index 
      end 
    end 

    it "should redirect to candies" do 
      get :index 
      response.should redirect_to candies_url
    end 
  end 

  describe "beware of Rails Cache" do 
    it "can be fine with a happy case" do 
      subject.i_assign_a_value

This file has been truncated. show original

you seed the cache. And then run it again without the happy case:

github.com

softwaregravy/rspec-troubleshoot/blob/1e36222e64bfd9c473be06fba0a5fa102d4bf0f6/spec/controllers/application_controller_spec.rb


require 'spec_helper'

describe ApplicationController do 
  describe "#redirect_to_candies" do 
    controller do 
      before_filter :redirect_to_candies 
      def index 
      end 
    end 

    it "should redirect to candies" do 
      get :index 
      response.should redirect_to candies_url
    end 
  end 

  describe "beware of Rails Cache" do 
#    it "can be fine with a happy case" do 
#      subject.i_assign_a_value

This file has been truncated. show original

You continue to get the failing test because the results of that block
are
cached.

Now, I’m not that familiar with Rails caching. But it appears that
there
might be an issue in which Rails is not respecting the perform_caching
flag.
If that’s not the root cause, then it seems to be that rspec could be
doing
a Rails.cache.clear and/or overriding a memory cache to be used during
tests.

Thoughts?

*** LOCAL GEMS ***

abstract (1.0.0)
actionmailer (3.0.9, 3.0.5)
actionpack (3.0.9, 3.0.5)
activemodel (3.0.9, 3.0.5)
activerecord (3.0.9, 3.0.5)
activeresource (3.0.9, 3.0.5)
activesupport (3.0.9, 3.0.5)
arel (2.0.10)
builder (2.1.2)
bundler (1.0.15)
diff-lcs (1.1.2)
erubis (2.6.6)
i18n (0.6.0, 0.5.0)
mail (2.2.19)
mime-types (1.16)
polyglot (0.3.1)
rack (1.2.3)
rack-mount (0.6.14)
rack-test (0.5.7)
rails (3.0.9, 3.0.5)
railties (3.0.9, 3.0.5)
rake (0.8.7)
rdoc (3.8)
rspec (2.6.0)
rspec-core (2.6.4)
rspec-expectations (2.6.0)
rspec-mocks (2.6.0)
rspec-rails (2.6.1)
sqlite3 (1.3.3)
thor (0.14.6)
treetop (1.4.9)
tzinfo (0.3.29)

ruby-1.9.2-p180@rspec-troubleshoot:

system:
uname: “Darwin John-Hinnegans-MacBook-Pro.local 10.8.0 Darwin
Kernel Version 10.8.0: Tue Jun 7 16:33:36 PDT 2011;
root:xnu-1504.15.3~1/RELEASE_I386 i386”
bash: “/bin/bash => GNU bash, version 3.2.48(1)-release
(x86_64-apple-darwin10.0)”
zsh: “/bin/zsh => zsh 4.3.9 (i386-apple-darwin10.0)”

rvm:
version: “rvm 1.2.8 by Wayne E. Seguin ([email protected])
[
http://rvm.beginrescueend.com/]”

ruby:
interpreter: “ruby”
version: “1.9.2p180”
date: “2011-02-18”
platform: “x86_64-darwin10.6.0”
patchlevel: “2011-02-18 revision 30909”
full_version: “ruby 1.9.2p180 (2011-02-18 revision 30909)
[x86_64-darwin10.6.0]”

jh100000 · July 3, 2011, 11:59am

On Jul 3, 2011, at 1:08 AM, John H. wrote:

you seed the cache. And then run it again without the happy case:

github.com

softwaregravy/rspec-troubleshoot/blob/1e36222e64bfd9c473be06fba0a5fa102d4bf0f6/spec/controllers/application_controller_spec.rb


require 'spec_helper'

describe ApplicationController do 
  describe "#redirect_to_candies" do 
    controller do 
      before_filter :redirect_to_candies 
      def index 
      end 
    end 

    it "should redirect to candies" do 
      get :index 
      response.should redirect_to candies_url
    end 
  end 

  describe "beware of Rails Cache" do 
#    it "can be fine with a happy case" do 
#      subject.i_assign_a_value

This file has been truncated. show original

You continue to get the failing test because the results of that block are
cached.

Now, I’m not that familiar with Rails caching. But it appears that there might
be an issue in which Rails is not respecting the perform_caching flag.

Looks like the perform_caching config option only impacts page caching.

See
http://pivotallabs.com/users/spierson/blog/articles/818-standup-04-30-2009-perform-caching-and-rails-cache-w3c-dtds-and-ie-range-min-max
for a brief discussion of options (that’s the first hit in a google
search for “perform_caching”, btw).

If that’s not the root cause, then it seems to be that rspec could be doing a
Rails.cache.clear and/or overriding a memory cache to be used during tests.

You can definitely do this yourself in a global before hook, but I don’t
know how people use Rails.cache in the wild and wouldn’t want to do
anything implicit that might break existing suites.

I’d recommend using a global before hook or raising an issue in the
rails tracker.

HTH,
David