rspec_prettyprint

Failure/Error: subject.user.should == existing_user
     private method `pretty_print' called for #<RSpec::Mocks::ErrorGenerator:0x00000106168148>
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:236:in `block (3 levels) in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:234:in `block (2 levels) in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:223:in `block in seplist'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:217:in `each'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:217:in `seplist'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:229:in `block in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:178:in `object_address_group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:228:in `pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:298:in `pretty_print'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:236:in `block (3 levels) in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:234:in `block (2 levels) in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:223:in `block in seplist'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:217:in `each'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:217:in `seplist'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:229:in `block in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:178:in `object_address_group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:228:in `pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:298:in `pretty_print'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:236:in `block (3 levels) in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:234:in `block (2 levels) in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:223:in `block in seplist'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:217:in `each'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:217:in `seplist'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:229:in `block in pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:178:in `object_address_group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:228:in `pp_object'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:298:in `pretty_print'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:154:in `pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:77:in `block in pp'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:121:in `guard_inspect_key'
     # /Users/txus/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/pp.rb:77:in `pp'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-expectations-2.2.0/lib/rspec/expectations/differ.rb:45:in `diff_as_object'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-expectations-2.2.0/lib/rspec/expectations/fail_with.rb:25:in `fail_with'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-expectations-2.2.0/lib/rspec/matchers/operator_matcher.rb:48:in `fail_with_message'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-expectations-2.2.0/lib/rspec/matchers/operator_matcher.rb:70:in `__delegate_operator'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-expectations-2.2.0/lib/rspec/matchers/operator_matcher.rb:60:in `eval_match'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-expectations-2.2.0/lib/rspec/matchers/operator_matcher.rb:29:in `block in use_custom_matcher_or_delegate'
     # ./spec/models/attendee_spec.rb:25:in `block (5 levels) in <top (required)>'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:40:in `instance_eval'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:40:in `block (2 levels) in run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:88:in `with_around_hooks'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:37:in `block in run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:81:in `block in with_pending_capture'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:80:in `catch'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:80:in `with_pending_capture'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example.rb:36:in `run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:261:in `block in run_examples'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:257:in `map'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:257:in `run_examples'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:231:in `run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `block in run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `map'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `block in run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `map'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `block in run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `map'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/example_group.rb:232:in `run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/command_line.rb:27:in `block (2 levels) in run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/command_line.rb:27:in `map'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/command_line.rb:27:in `block in run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/reporter.rb:12:in `report'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/command_line.rb:24:in `run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/runner.rb:55:in `run_in_process'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/runner.rb:46:in `run'
     # /Users/txus/.rvm/gems/ruby-1.9.2-p0@confly/gems/rspec-core-2.2.1/lib/rspec/core/runner.rb:10:in `block in autorun'

Did you ever find a fix for this? Encountering this same thing on a project with a similar looking stack trace.

Failure/Error: download.calculate_rarity.should == [piece3, piece1, piece2]
 NoMethodError:
   private method `pretty_print' called for #<RSpec::Mocks::ErrorGenerator:0x0000010223eee0>
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:236:in `block (3 levels) in pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:234:in `block (2 levels) in pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:223:in `block in seplist'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:217:in `each'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:217:in `seplist'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:229:in `block in pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:178:in `object_address_group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:228:in `pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:298:in `pretty_print'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:236:in `block (3 levels) in pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:234:in `block (2 levels) in pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:223:in `block in seplist'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:217:in `each'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:217:in `seplist'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:229:in `block in pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:178:in `object_address_group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:228:in `pp_object'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:298:in `pretty_print'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:339:in `block (2 levels) in pretty_print'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:223:in `block in seplist'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:217:in `each'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:217:in `seplist'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:338:in `block in pretty_print'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:337:in `pretty_print'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `block in pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:199:in `block (2 levels) in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:225:in `nest'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:198:in `block in group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:210:in `group_sub'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/prettyprint.rb:197:in `group'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:154:in `pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:77:in `block in pp'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:121:in `guard_inspect_key'
 # /Users/blake/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/pp.rb:77:in `pp'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-expectations-2.6.0/lib/rspec/expectations/differ.rb:45:in `diff_as_object'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-expectations-2.6.0/lib/rspec/expectations/fail_with.rb:25:in `fail_with'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-expectations-2.6.0/lib/rspec/matchers/operator_matcher.rb:48:in `fail_with_message'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-expectations-2.6.0/lib/rspec/matchers/operator_matcher.rb:70:in `__delegate_operator'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-expectations-2.6.0/lib/rspec/matchers/operator_matcher.rb:60:in `eval_match'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-expectations-2.6.0/lib/rspec/matchers/operator_matcher.rb:29:in `block in use_custom_matcher_or_delegate'
 # ./spec/unit/download_spec.rb:353:in `block (3 levels) in <top (required)>'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example.rb:48:in `instance_eval'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example.rb:48:in `block in run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example.rb:107:in `with_around_hooks'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example.rb:45:in `run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example_group.rb:294:in `block in run_examples'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example_group.rb:290:in `map'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example_group.rb:290:in `run_examples'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example_group.rb:262:in `run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example_group.rb:263:in `block in run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example_group.rb:263:in `map'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/example_group.rb:263:in `run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/command_line.rb:24:in `block (2 levels) in run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/command_line.rb:24:in `map'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/command_line.rb:24:in `block in run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/reporter.rb:12:in `report'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/command_line.rb:21:in `run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/runner.rb:80:in `run_in_process'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/runner.rb:69:in `run'
 # /Users/blake/.rvm/gems/ruby-1.9.2-p180@em-bittorrent/gems/rspec-core-2.6.3/lib/rspec/core/runner.rb:11:in `block in autorun'

Finished in 0.00297 seconds
1 example, 1 failure

It seems that it eventually worked without changing a line (now that part of the code is the same). The working version of that spec uses RSpec 2.3.0, and the failing was using 2.2.1.
Maybe it is a bug reintroduced somewhere between 2.3 and 2.6? You should try activating RSpec 2.3.0 in your Gemfile. Keep me posted!

I'm also running into this, tried 2.3, 2.4, 2.5 and 2.6.

This exception goes away when the test actually passes, but I never got to the root cause.

I just ran into this and fixed the issue. (no idea if this applies to anyone else).

I had:

But the object called only had one order method being called. Once I removed the extra/ order from stub_chain, the test passed and all was fine.

I got similar error this when I was doing this:
--BAD SYNTAX-- assert_response redirect_to(forums_url) --BAD SYNTAX--

When I should have been doing this:
response.should be_redirect(forums_url)

Calls:
flunk(build_message(message, "Expected response to be a , but was ", type, @response.response_code))

Which calls:
template.gsub(/\G((?:[^]|.)*?)()??/) { $1 + ($2 ? "?" : mu_pp(arguments.shift)) } (mu_pp bombs out)

Seems to be fine once you fix the broken test.

Pretty Print is calling #inspect on an object without a #to_s.

Add this to your class:

def to_s
  "something you want to see when this is inspected"
end