Cannot call Contract in AS#included block

[PikachuEXE]

Env

MRI 2.2.2 or 2.2.3

What happened

• I extended a class (e.g. Post) with a module (e.g. ClassMethods) where ClassMethods has included Contracts
• When I call Contract method inside Post after including ClassMethods:
  • It works fine in 0.9
  • It raises an error in 0.10.1 or 0.11.0 (see the Error section below)

To reproduce the error please look at the test script gist
Too long to read? Shorter version: https://gist.github.com/PikachuEXE/1672d5c0434863bee6ae

Error

Message from application: undefined method `Contract' for Class:Class (NoMethodError)

Updates

Update 1: Even after I have removed ActiveSupport::Concern usage (and switch to Module#included, it's still failing. So I updated the code to ensure it's not AS related.
Update 2: Included Ruby versions
Update 3: Added test script gist
Update 4: Update the test script again (removed AS dependency)

[PikachuEXE]

Still no idea what causes this yet, too many commits to read :S

[PikachuEXE]

I have the following AR model:

require "contracts"
require "contracts/version"

class Agency < ActiveRecord::Base
  p Contracts::VERSION
  include Contracts
  p respond_to?(:Contract)
  p method(:Contract).source_location

  p Contract None => Any
  def whatever_1
  end

  include ConcernModule

  module ConcernModule
    extend ActiveSupport::Concern

    included do
      include Contracts
      p respond_to?(:Contract)
      p method(:Contract).source_location

      p None => Any
      def whatever_2
      end
    end
  end
  # rest
end

For 0.9:

"0.9"
true
["/Users/PikachuEXE/.rvm/gems/ruby-2.2.2/gems/contracts-0.9/lib/contracts/decorators.rb", 222]
[[Contract, [{Contracts::None=>Contracts::Any}]]]
true
["/Users/PikachuEXE/.rvm/gems/ruby-2.2.2/gems/contracts-0.9/lib/contracts/decorators.rb", 222]
[[Contract, [{Contracts::None=>Contracts::Any}]]]

For 0.10:

"0.10"
true
["/Users/PikachuEXE/.rvm/gems/ruby-2.2.2/gems/contracts-0.10/lib/contracts/decorators.rb", 32]
[[Contract, [{Contracts::None=>Contracts::Any}]]]
true
["/Users/PikachuEXE/.rvm/gems/ruby-2.2.2/gems/contracts-0.10/lib/contracts.rb", 41]
/Users/PikachuEXE/.rvm/gems/ruby-2.2.2/gems/contracts-0.10/lib/contracts.rb:42:in `Contract': undefined method `Contract' for Class:Class (NoMethodError)

[egonSchiele]

Ugh, wonder how this happened. Thanks for reporting.

[waterlink]

Might be related to engine refactoring. If you look at the output of #source_location you will see, that in second case it is different. And in this place it tries to do self.class.Contract(*args). And class of current object doesn't have Contract method.

And Class:Class there scares me. That means that it is already being called on class of the class, and on top it tries to go even further and call it on Class of Class of YourClass. ie:

YourClass     # => YourClass
_.class       # => Class
_.class       # => Class:Class     <------ this is exactly what `Contract` try to being called on..

[PikachuEXE]

0.11.0 has not fixed this issue

[PikachuEXE]

Any update on this yet?

[egonSchiele]

Nope...I need to do a git bisect when I have some time...

[waterlink]

I will look into it today (2-2.5 hours) later.

[waterlink]

@PikachuEXE I don't have this problem on active* = 4.2.4 and with contracts = 0.11.0. Though I had to use Contract Contracts::None => Contracts::Any because include in block does not change syntactical scope.

Which version of active* do you have?

[waterlink]

Just tried following versions too, and all of them worked:

• = 4.2.4
• = 4.1.13
• = 4.0.13
• = 3.2.22

[waterlink]

And what about ruby version, BTW ?

[PikachuEXE]

Sorry for not providing those ;P
I am switching away from AS Concern
And this problem can be reproduced with the replacement #class_eval & #included hook
Reproduced on MRI 2.2.2 & 2.2.3

[waterlink]

So if you say, that code is AS/AR independent, can it be rewritten like this?:

class Something
  module WithSettings
    def self.included(base)
      base.class_eval do
        include Contracts

        Contract None => ArrayOf[String]
        def emails
          #...
        end
      end
    end
  end
end

?

[waterlink]

So, I'm trying to run this guy: https://gist.github.com/waterlink/ca3080bfee096fa7d08a
with:

contracts: 0.11.0
ruby: 2.2.3

And I don't get any strange error. Everything works just fine..

@PikachuEXE do you see anything I am not doing correctly to reproduce the bug?

[PikachuEXE]

Let me create a test script that can reproduce the bug at work...
I am not at work now :P

[PikachuEXE]

OK test script gist created: https://gist.github.com/PikachuEXE/e7efb3a58ef3c9764722

[alex-fedorov]

Well, code definitely is AS dependent. Removing extend ActiveSupport::Concern makes it work.

[waterlink]

Nailed it down to: https://gist.github.com/waterlink/0018249f6c3b86403d87

[PikachuEXE]

Got a more simple version than my previous gist: https://gist.github.com/PikachuEXE/1672d5c0434863bee6ae

Not much different from https://gist.github.com/waterlink/0018249f6c3b86403d87
But added 2 examples:

• extending Contracts in class
• including Contracts in singleton class
  They both pass