Rake: no such file to load -- xpath - ruby-on-rails

Question

How do I resolve the following error?
bundle exec rake db:create
rake aborted!
no such file to load -- xpath
/Users/michael/Sites/appsbar/config/application.rb:13:in `<top (required)>'
/Users/michael/Sites/appsbar/Rakefile:5:in `require'
/Users/michael/Sites/appsbar/Rakefile:5:in `<top (required)>'
with trace
bundle exec rake db:create --trace
rake aborted!
no such file to load -- xpath
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `block in require'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:236:in `load_dependency'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/capybara-2.0.1/lib/capybara.rb:3:in `<top (required)>'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/bundler-1.2.2/lib/bundler/runtime.rb:68:in `require'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/bundler-1.2.2/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/bundler-1.2.2/lib/bundler/runtime.rb:66:in `each'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/bundler-1.2.2/lib/bundler/runtime.rb:66:in `block in require'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/bundler-1.2.2/lib/bundler/runtime.rb:55:in `each'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/bundler-1.2.2/lib/bundler/runtime.rb:55:in `require'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/bundler-1.2.2/lib/bundler.rb:128:in `require'
/Users/michael/Sites/appsbar/config/application.rb:13:in `<top (required)>'
/Users/michael/Sites/appsbar/Rakefile:5:in `require'
/Users/michael/Sites/appsbar/Rakefile:5:in `<top (required)>'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/rake_module.rb:25:in `load'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/rake_module.rb:25:in `load_rakefile'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/application.rb:581:in `raw_load_rakefile'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/application.rb:87:in `block in load_rakefile'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/application.rb:158:in `standard_exception_handling'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/application.rb:86:in `load_rakefile'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/application.rb:70:in `block in run'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/application.rb:158:in `standard_exception_handling'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/lib/rake/application.rb:68:in `run'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/gems/rake-10.0.2/bin/rake:37:in `<top (required)>'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/bin/rake:19:in `load'
/Users/michael/.rbenv/versions/1.9.2-p290/gemsets/appsbar/bin/rake:19:in `<main>'
application.rb
require File.expand_path('../boot', __FILE__)
# Pick the frameworks you want:
require "active_record/railtie"
require "action_controller/railtie"
require "action_mailer/railtie"
require "active_resource/railtie"
require "sprockets/railtie"
# require "rails/test_unit/railtie"
if defined?(Bundler)
# If you precompile assets before deploying to production, use this line
Bundler.require(*Rails.groups(:assets => %w(development test)))
# If you want your assets lazily compiled in production, use this line
# Bundler.require(:default, :assets, Rails.env)
end
module Appsbar
class Application < Rails::Application
# Settings in config/environments/* take precedence over those specified here.
# Application configuration should go into files in config/initializers
# -- all .rb files in that directory are automatically loaded.
# Custom directories with classes and modules you want to be autoloadable.
# config.autoload_paths += %W(#{config.root}/extras)
# Only load the plugins named here, in the order given (default is alphabetical).
# :all can be used as a placeholder for all plugins not explicitly named.
# config.plugins = [ :exception_notification, :ssl_requirement, :all ]
# Activate observers that should always be running.
# config.active_record.observers = :cacher, :garbage_collector, :forum_observer
# Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
# Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
# config.time_zone = 'Central Time (US & Canada)'
# The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
# config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
# config.i18n.default_locale = :de
# Configure the default encoding used in templates for Ruby 1.9.
config.encoding = "utf-8"
# Configure sensitive parameters which will be filtered from the log file.
config.filter_parameters += [:password]
# Enable escaping HTML in JSON.
config.active_support.escape_html_entities_in_json = true
# Use SQL instead of Active Record's schema dumper when creating the database.
# This is necessary if your schema can't be completely dumped by the schema dumper,
# like if you have constraints or database-specific column types
# config.active_record.schema_format = :sql
# Enforce whitelist mode for mass assignment.
# This will create an empty whitelist of attributes available for mass-assignment for all models
# in your app. As such, your models will need to explicitly whitelist or blacklist accessible
# parameters by using an attr_accessible or attr_protected declaration.
config.active_record.whitelist_attributes = true
# Enable the asset pipeline
config.assets.enabled = true
# Version of your assets, change this if you want to expire all your assets
config.assets.version = '1.0'
# Devise recommendation:
# If you are deploying Rails 3.1 on Heroku, you may want to set:
# config.assets.initialize_on_precompile = false
# On config/application.rb forcing your application to not access the DB
# or load models when precompiling your assets.
config.assets.initialize_on_precompile = false
end
end
Rakefile
#!/usr/bin/env rake
# Add your own tasks in files placed in lib/tasks ending in .rake,
# for example lib/tasks/capistrano.rake, and they will automatically be available to Rake.
require File.expand_path('../config/application', __FILE__)
Appsbar::Application.load_tasks

Answer 1

See
https://github.com/jnicklas/capybara/issues/882
Some people have fixed this issue by redoing "bundle update capybara", this appears to fix some kind of bundler dependency weirdness.

Answer 2

/full/path/to/the/gem/being/used/bin/gem install 'xpath' please ensure you're using the right gem binary, for example, my ruby install is in $HOME/.rvm/bin/ruby and gem is in $HOME/.rvm/gems/ruby-1.9.3-p327/bin. It's also to be found in /usr/bin. I always run it as $HOME/.rvm/gems/ruby-1.9.3-p327/bin/ruby $HOME/.rvm/gems/ruby-1.9.3-p327/bin/gem to not be ambiguous and to ensure I'm getting the right one.