RSpec MustBeConfiguredBeforeExampleGroupsError on plain project

Question

I'm setting up a Rails 3.1 project and like to properly test it using RSpec.

After running rails g rspec:install and further running rspec, the console messages read as follows:

% rspec
/Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/configuration.rb:470:in `assert_no_example_groups_defined': RSpec's mock_framework configuration option must be configured before any example groups are defined, but you have already defined a group. (RSpec::Core::Configuration::MustBeConfiguredBeforeExampleGroupsError)
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/configuration.rb:168:in `mock_framework='
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/configuration.rb:142:in `mock_with'
    from /Users/ened/project/spec/controllers/../spec_helper.rb:19
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core.rb:71:in `configure'
    from /Users/ened/project/spec/controllers/../spec_helper.rb:11
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240:in `require'
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240:in `require'
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:225:in `load_dependency'
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240:in `require'
    from /Users/ened/project/spec/controllers/submissions_controller_spec.rb:1
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:234:in `load'
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:234:in `load'
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:225:in `load_dependency'
    from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:234:in `load'
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/configuration.rb:459:in `load_spec_files'
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/configuration.rb:459:in `map'
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/configuration.rb:459:in `load_spec_files'
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/command_line.rb:18:in `run'
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/runner.rb:80:in `run_in_process'
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/runner.rb:69:in `run'
    from /Library/Ruby/Gems/1.8/gems/rspec-core-2.7.0/lib/rspec/core/runner.rb:10:in `autorun'
    from /usr/bin/rspec:19

My rspec/spec_helper.rb looks like this:

# This file is copied to spec/ when you run 'rails generate rspec:install'
ENV["RAILS_ENV"] ||= 'test'
require File.expand_path("../../config/environment", __FILE__)
require 'rspec/rails'
require 'rspec/autorun'

# Requires supporting ruby files with custom matchers and macros, etc,
# in spec/support/ and its subdirectories.
Dir[Rails.root.join("spec/support/**/*.rb")].each {|f| require f}

RSpec.configure do |config|
  # == Mock Framework
  #
  # If you prefer to use mocha, flexmock or RR, uncomment the appropriate line:
  #
  # config.mock_with :mocha
  # config.mock_with :flexmock
  # config.mock_with :rr
  config.mock_with :rspec

  # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
  config.fixture_path = "#{::Rails.root}/spec/fixtures"

  # If you're not using ActiveRecord, or you'd prefer not to run each of your
  # examples within a transaction, remove the following line or assign false
  # instead of true.
  config.use_transactional_fixtures = true

  # If true, the base class of anonymous controllers will be inferred
  # automatically. This will be the default behavior in future versions of
  # rspec-rails.
  config.infer_base_class_for_anonymous_controllers = false
end

I thought it's configured already using the config.mock_with ? I'm puzzled, what is missing?

Answer 1

I just hit this. It turned out to be that some of my old (circa RSpec 1) specs had the following require statement:

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')

Most of the new specs had this require statement:

require 'spec_helper'

I'd never bothered to tidy up the old style. What this meant was that the spec_helper.rb filename was passed to require in two different ways: one full path, one local path. This in turn caused spec_helper.rb to be executed twice, triggering the error. Changing all the require statements to the short new style fixed the issue.