You need this awkward command:

page.driver.browser.action.move_to(page.find(selector).native).perform

Note that there are better ways for newer Capybaras.

Since Ruby 2.1, defining a method returns its name as a Symbol:

def foo() end             # => :foo
define_method :foo do end # => :foo

You can use this to do Python-like decorators like so:

private def foo; end 
memoize def foo; end 

"Keyword arguments" allow naming method arguments (optionally setting a default value). By using the double-splat operator, you can collect additional options. Default values for standard arguments still work (see adjective).

def greet(name, adjective = 'happy', suffix: '!', count: 7, **options)
  greeting = options[:letter] ? 'Dear' : 'Hello'
  puts "#{greeting} #{adjective} #{name + suffix * count}"
end

Invoke the method like this:

greet('Otto', 'sad', suffix: '??', count: 9, include_blank: true)

In Ruby 2.1+,...

Introduces :include_old_value option to :assignable_xxx method.

Now supports Rails 4.1 and Ruby 2.1.

Using this gem, whenever a Capybara test in Cucumber, Rspec or Minitest fails, the HTML for the failed page and a screenshot (when using capybara-webkit, Selenium or poltergeist) is saved into $APPLICATION_ROOT/tmp/capybara.

Link via Binärgewitter Podcast (German).

For me guard recently took a very long to start (as in "minutes"), because I had lots of images in public/system.

Upgrading the listen gem (which is a dependency) to 2.7.7 fixed this.

As you know, assignable_values does not invalidate a record even when an attribute value becomes unassignable. See this example about songs:

class Song < ActiveRecord::Base
  belongs_to :artist
  belongs_to :record_label

  assignable_values_for :artist do
    record_label.artists
  end
end

We'll create two record labels with one artist each and create a song for one artist. When we change the song's record label, its artist is still valid.

makandra = RecordLabel.create! name: 'makandra records'
dominik...

assignable_values now supports Rails 4.1 and Ruby 2.1.0.

Travis CI is a free continuous integration testing service. However, it is really fragile and will break more than it will work.

If you choose to use it anyway, learn the lessons we already learnt:

Use a compatible Rubygems for Rails 2.3 on Ruby 1.8.7

Ruby 1.8.7 is not compatible with current Rubygems versions (> 2.0). Runnig rvm rubygems latest-1.8 --force will fix this and install Rubygems version 1.8.29.

To make Travis CI do this, add `before_script: rvm rubygems latest-1....

A little-known feature of modern Regexp engines that help when optimizing a pattern that will be matched against long strings:

An atomic group is a group that, when the regex engine exits from it, automatically throws away all backtracking positions remembered by any tokens inside the group.

When you tell rbenv to install a Ruby it does not know about, you will get an error message.

$ rbenv install 2.1.2
ruby-build: definition not found: 2.1.2

You can list all available versions with `rbenv install --list'.

If the version you're looking for is not present, first try upgrading
ruby-build. If it's still missing, open a request on the ruby-build
issue tracker: https://github.com/sstephenson/ruby-build/issues

(Fun fact: Recent versions of ruby-build will give you a more helpful error message which...

EdgeRider 0.3.0 adds support for Rails 4.1 and Ruby 2.1. It forward-ports ActiveRecord::Base.scoped to Rails 4.1.

RSpec 3.0 deprecates the :should way of writing specs for expecting things to happen.

However, if you have tests you cannot change (e.g. because they are inside a gem, spanning multiple versions of Rails and RSpec), you can explicitly allow the deprecated syntax.

Fix

Inside spec/spec_helpber.rb, set rspec-expectations’ and/or rspec-mocks’ syntax as following:

RSpec.configure do |config|
  # ...
  config.mock_with :rspec do |c|
    c.syntax = [:should, :expect]
 ...

Sometimes you're getting an ActiveSupport deprecation warning that you cannot or don't want to fix. In these cases, it might be okay to silence some specific warnings. Add this to your initializers, or require it in your tests:

silenced = [
  /Not considered a useful test/,
  /use: should(_not)? have_sent_email/,
] # list of warnings you want to silence

silenced_expr = Regexp.new(silenced.join('|'))

ActiveSupport::Deprecation.behavior = lambda do |msg, stack|
  unless msg =~ silenced_expr
    ActiveSupport::Deprecation::DEFAULT_BEHAVI...

Warnings like those below may originate from rspec or shoulda-matchers or other gems that have not updated yet to the new MiniTest API.

One

Warning: you should require 'minitest/autorun' instead.
Warning: or add 'gem "minitest"' before 'require "minitest/autorun"'
# (backtrace)

Solution: Add gem 'minitest' to your Gemfile, before any rspec gem.

Another

MiniTest::Unit::TestCase is now Minitest::Test. From /Users/makandra/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/1.9.1/tes...

jQuery plugin that makes it easy to dynamically add and remove records when using ActiveRecord's nested attributes.

ActiveRecord caches results of SQL queries. If you want to discard the cached results for one model, you can call MyModel.connection.clear_query_cache.

SimpleForm is a great approach to simplifying your forms, and it comes with lots of well-defined input types. However, the :grouped_select type seems to be overly complicated for most use cases.

Example

Consider this example, from the documentation:

form.input :country_id, collection: @continents,
  as: :grouped_select, group_method: :countries

While that looks easy enough at a first glance, look closer. The example passes @continents for a country_id.\
SimpleForm actua...

MuPDF is a PDF reader that renders very quickly, yet still correctly.

It supports PDF 1.7 and all the fancy shenanigans that evince (Ubuntu's default PDF reader) fails to render properly.

On Ubuntu, MuPDF is available in the Universe sources. Simply install via APT:

sudo apt-get install mupdf

Interaction primarily happens via keyboard, but there is basic mouse support.\
See the manpage for more details on navigating.

One downside: There is no printing support, so if...

So you want your Ruby script to install missing gems instead of dying? Take this method:

def installing_missing_gems(&block)
  yield
rescue LoadError => e
  gem_name = e.message.split('--').last.strip
  install_command = 'gem install ' + gem_name
  
  # install missing gem
  puts 'Probably missing gem: ' + gem_name
  print 'Auto-install it? [yN] '
  gets.strip =~ /y/i or exit(1)
  system(install_command) or exit(1)
  
  # retry
  Gem.clear_paths
  puts 'Trying again ...'
  require gem_name
  retry
end

Use it like this:

insta...

This is a great tutorials for beginners and intermediate AngularJS developers. It covers a lot of ground, including routing and data transfer between client and server.

The information in this card is only relevant for Rails 2.3-era apps.

This note gives a quick introduction into caching methods (page caching, action caching and fragment caching) in rails and describes some specific problems and solutions.

The descriptions below are valid for Rails 2 and 3. Recently, caching with timestamp- or content-based keys has become more popular which saves you the pain of invalidating stale caches.

How to enable/disable caching

To enable or disable caching in rails you ca...