Rspec any_instance stub causing error undefined method __rspec_original_dup

Question

I'm trying to stub out a Class method for any instance of the class (via any_instance). My tests run through successfully, but at the end of the test when rspec is trying to reset the any_instance stub, it throws an error (Unable to find matching line from backtrace). Here's the apparent culprit line of code (removing it removes the error):

Confetti::Config.any_instance.stub(:write_info)

The full error is below. Seems like stub should've (but fails to) created the __rspec_original_dup method, and when the reset happens, it can't find the expected method.

 Failure/Error: Unable to find matching line from backtrace
 NameError:
   undefined method `__rspec_original_dup' for class `Confetti::Config'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/any_instance.rb:73:in `alias_method'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/any_instance.rb:73:in `restore_dup'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/any_instance.rb:72:in `class_eval'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/any_instance.rb:72:in `restore_dup'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/any_instance.rb:46:in `rspec_reset'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/space.rb:17:in `reset_all'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/space.rb:16:in `each'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks/space.rb:16:in `reset_all'
 # /Library/Ruby/Gems/1.8/gems/rspec-mocks-2.11.1/lib/rspec/mocks.rb:23:in `teardown'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/mocking/with_rspec.rb:18:in `teardown_mocks_for_rspec'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example.rb:308:in `run_after_each'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example.rb:119:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example.rb:253:in `with_around_each_hooks'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example.rb:110:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example_group.rb:378:in `run_examples'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example_group.rb:374:in `map'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example_group.rb:374:in `run_examples'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example_group.rb:360:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example_group.rb:361:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example_group.rb:361:in `map'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/example_group.rb:361:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/command_line.rb:28:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/command_line.rb:28:in `map'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/command_line.rb:28:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/reporter.rb:34:in `report'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/command_line.rb:25:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/runner.rb:69:in `run'
 # /Library/Ruby/Gems/1.8/gems/rspec-core-2.11.1/lib/rspec/core/runner.rb:8:in `autorun'
 # /usr/bin/rspec:19

Looks like you're using OSX system Ruby. Does it work if you use RVM or rbenv? I ask because we're seeing the same behavior, but only for devs running OSX system Ruby. — bobocopy
Getting something similar after upgrading to RSpec 2.11. I use Ruby 1.9.3 from RVM, though on OS X, if that has any relevance. I do ThinkingSphinx::Search.any_instance.stub(:error) and get the error undefined method `dup' for class `ThinkingSphinx::Search' with this in the backtrace: /Users/henrik/.rvm/gems/ruby-1.9.3-p0-patched@foobar/gems/rspec-mocks-2.11.1/lib/rspec/mocks/any_instance.rb:64:in `alias_method'. — Henrik N

Benjamin Oakes Benjamin Oakes · Accepted Answer · 2012-10-19T22:25:46

I solved this by simply using Rspec v2.10.0 instead of v2.11.0:

gem 'rspec', '~> 2.10.0'

From the links that Henrik provided, it sounds like they may release a bugfix for Rspec. Watch this issue for more information. In the meantime, downgrading solved the issue for me.

(Thanks for your work in helping me figure this out, Henrik.)

Rspec any_instance stub causing error undefined method __rspec_original_dup

1 Answers