This card describes how to pass an array with multiple element to a JavaScript function, so that the first array element becomes the first function argument, the second element becomes the second argument, etc.

Note how this is different from passing the entire array as the first argument. Compare these two different ways of calling fun() in Ruby:

# Ruby
array = [1, 2, 3]
fun(array)  # same as fun([1, 2, 3]) (1 argument)
fun(*array) # same as fun(1, 2, 3)   (3 arguments)

Depending on your culture the spreading of array eleme...

So you're getting an error message like the following, although your Gemfile lists shoulda-matchers and it has always worked:

NoMethodError:
  undefined method `allow_value' for #<RSpec::ExampleGroups::Person::Age:0x007feb239fa6a8>

This is due to Rails 4.1 (specifically, Spring) revealing a weak point of shoulda-matchers -- jonleighton explains why.

Solution

The solution is to follow [the gem's installation guide](https://github.com/thoughtbot/sh...

Provides a value container that guarantees atomic updates to this value in a multi-threaded Ruby program.

Originally linked to:
ruby-concurrency/atomic (Deprecated)

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+,...

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....

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]
 ...

When you have a string containing umlauts which don't behave as expected (are not matched with a regexp, can't be found with an SQL query, do not print correctly on LaTeX documents, etc), you may be encountering umlauts which are not actually umlaut characters.

They look, depending on the font, like their "real" umlaut counterpart:

• ä ↔ ä
• ö ↔ ö
• ü ↔ ü

However, they are not the same:

'ä' == 'ä' # false
'ä'.size # 1
'ä'.size # 2

Looking at how those strings are constructed reveals what is going on:

'ä'.unpack('U*...

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...

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...

If you parse this Yaml ...

yes: 'Totally'
no: 'Nope'

... you get this Ruby hash:

{ true: 'Totally',
  false: 'Nope' }

In order to use the strings 'yes' and 'no' as keys, you need to wrap them with quotes:

'yes': 'Totally'
'no': 'Nope'

There's actually a long list of reserved words with this behavior:

y|Y|yes|Yes|YES|n|N|no|No|NO
|true|True|TRUE|false|False|FALSE
|on|On|ON|off|Off|OFF

I'm sorry.

You are probably using Ruby 1.8.7 with a too recent versions of Rubygems.

Downgrade your Rubygems to the latest version that works with 1.8.7.

See also

• Fix Rubygems warning: Gem.source_index is deprecated, use Specification
• Fix Rubygems binary error: undefined method `activate_bin_path' for Gem:Module (NoMethodError)
• [Bundler: Gemfile.lock is corrupt & gems are missing from the DEP...

There are 3 built-in file descriptors: stdin, stdout and stderr (std=standard). (You can define your own, see the linked article.)

Basic

• 0/1/2 references stdin/stdout/stderr
• >/2> redirects stdout/stderr, where > is taken as 1>
• &1/&2 references stdout/stderr
• &> redirects stdout and stderr = everything (caution: see below)

Caution: &> is functional as of Bash 4. This seems to result in a slightly differing behaviour when redirecting output in Ru...

Create, or edit your ~/.irbrc file to include:

require 'irb/ext/eval_history' # was 'irb/ext/save-history' for versions prior to Ruby 3.3
IRB.conf[:SAVE_HISTORY] = 2000
IRB.conf[:HISTORY_FILE] = "#{ENV['HOME']}/.irb-history"

quiet_assets helps with disabling asset pipeline log messages in the development log. When the gem is added, asset pipeline logs are suppressed by default.

If you want to disable muting temporarily, add config.quiet_assets = false to your config/application.rb.