When you are working with Backbone models and inheritance, at some point you want to overwrite inherited methods but call the parent's implementation, too.
In JavaScript, there is no simple "super" method like in Ruby -- so here is how to do it with Backbone.

Example

BaseClass = Backbone.Model.extend({
  initialize: function(options) {
    console.log(options.baseInfo);
  }
});

MyClass = BaseClass.extend({
  initialize: function(options) {
    console.log(options.myInfo);
  }
});

ne...

Sometimes you have a test expectation but actually want a better error message in case of a failure. Here is how to do that.

Background

Consider this test:

expect(User.last).to be_present

In case of an error, it will fail with a not-so-helpful error message:

expected present? to return true, got false (Spec::Expectations::ExpectationNotMetError)

Solution

That can be fixed easily. RSpec expectations allow you to pass an error message like this:

expect(User.last).to be_present, 'Could not find a user!'

...

Mornings can be rough. To make them a little easier, leave yourself a failing test if your work isn’t finished. When you come back to the project, it makes it much easier to understand where you were and figure out what you still need to do.

After I upgraded to Mac OS X Mavericks, I regularly got this error message when running Cucumber features with Selenium:

Element cannot be scrolled into view:[object XrayWrapper [object HTMLInputElement]] (Selenium::WebDriver::Error::MoveTargetOutOfBoundsError)

I had the Terminal window running the test on my secondary screen, whereas the Selenium-webdriven Firefox always started on my primary one. Now if I had focused the secondary screen when running the tests, Selenium could not start Firefox and switch to it (probably because t...

Warning: Because of (unclear) rounding issues and missing decimal places (see examples below),
do NOT use this when dealing with money. Use our amount helper instead.

In Ruby, you can easily format strings using % (short for Kernel#sprintf):

'%.2f' % 1.23456 #=> 1.23
'%.2f' % 2 #=> 2.00

However, what if you only want the decimals to be shown if they matter? There is g! It will limit the total number of displayed digits, disregarding...

About

A MySQL DECIMAL column is used when it is important to preserve exact precision. It takes two parameters, where precision is the total number of digits and scale the number of digits to the right of the decimal point. A DECIMAL(6,2) column may store numbers up to 9,999.99.

In Rails, a decimal column definition looks like this: t.decimal :amount, :precision => 6, :scale => 2.

Issue

MySQL prior to 5.6 stored leading zeros (0003.1) and +/- characters (+2.1) within the column. However, **it would permit storing ...

We have released Modularity 2. It has many incompatible changes. See below for a script to migrate your applications automatically.

There is no does method anymore

We now use traits with the vanilla include method:

class Article < ActiveRecord::Base
  include DoesTrashable
end

When your trait has parameters, use square brackets:

class Article < ActiveRecord::Base
  include DoesStripFields[:name, :brand]
end

Note how you ...

If you want to test that a certain text is contained within the document title of your page, you can do so using Selenium and a step such as

Then /^"(.*?)" should be shown in the document title$/ do |expectation|
  title = page.driver.browser.title
  title.should include(expectation)
end

When you do something like this in your code:

def var_value
  @var ||= some_expensive_calculation
end

Be aware that it will run some_expensive_calculation every time you call var_value if some_expensive_calculation returns nil.

This illustrates the problem:

def some_expensive_calculation
  puts "i am off shopping bits!"
  @some_expensive_calculations_result
end

When you set @some_expensive_calculations_result to nil, ||= runs some_expensive_calculation every time....

TLDR: This card explains which threads and processes interact with each other when you run a Selenium test with Capybara. This will help you understand "impossible" behavior of your tests.

When you run a Rack::Test (non-Javascript) test with Capybara, there is a single process in play. It runs both your test script and the server responding to the user interactions scripted by your test.

A Selenium (Javascript) test has a lot more moving parts:

1. One process runs your test script. This is the process you...

When you print something from within your .bashrc file you will run into trouble when copying something onto your machine using scp for example.

This is because the output from your .bashrc interferes with scp. The solution is to decide whether the bash shell is started interactively (you start a terminal on your screen) or not (scp).

if [ ! -z "$PS1" ]; then
  # This happens in interactive shells only and does not interfere with scp.
  echo "Learn!"
fi

# Attach a file
#
# Example:
#
#   Company.new.logo = File.new…
#
#   Given the file "…" was attached as logo to the company above
#
#
# Example:
#
#   class Gallery
#     has_many :images, :as => :owner
#   end
#
#   class Image
#     belongs_to :owner, polymorphic: true
#   end
#
#   # so container = Image.new; container.file = File.new… , container.owner = object
#
#   Given the file "…" was attached as Image/file to the company above
#
#
# Example:
#
#   Set updated_at with
#
#     Given … above at "2011-11-11 11:11"
#

This error occurs when you already have a database.yml which defines the database for the cucumber environment instead of test. (Spreewald database.sample.yml has changed)

Fix

Change cucumber to test in your databse.yml

test:    # <---
  adapter: mysql2
  database: spreewald_test
  encoding: utf8
  host: localhost
  username: root
  password: password

Say you have a User with a Carrierwave attribute #avatar:

class User < ActiveRecord::Base
  mount_uploader :avatar, AvatarUploader
end

When whitelisting the avatar field in the controller, you might do this:

params[:user].permit(:avatar)

But you probably want this:

params[:user].permit(:avatar, :avatar_cache, :remove_avatar)

In this example:

• :avatar_cache allows a newly upload image to persist through form roundtrips in the case of validation errors (something that isn't possibl...

When you want to find out the data type of an attribute, you can just use ActiveRecord's columns_hash method.

It returns a hash of column objects that include a type attribute (and more database-related information).

Example:

Contract.columns_hash['id'].type
 => :integer
Contract.columns_hash['active'].type
 => :boolean
Contract.columns_hash['updated_at'].type
 => :datetime

If you get a Quota error with OpenStack, it doesn't have to be what it tell.

For example, I've got this message because the RAM Quota was exceed:

2013-11-11 17:13:25 WARNING nova.compute.api [req-bdasdfas-f5d7-4fcd-bf1b-asdfasdf229e ba2c21dadasdfasdf1d6asdfasdfa0f bfe2db2aasdfasdfb8ea686asdfasdfb] Quota exceeded for bfe2db2aasdfasdfb8ea686asdfasdfb, tried to run 1 instances. Cannot run any more instances of this type.
2013-11-11 17:13:25 INFO nova.api.openstack.wsgi [req-bd003113-f5d7-4fcd-bf1b-asdfasdf229e ba2c21dadasdfasdf1d6asdf...

Sometimes you need to monitor a connection from your machine to a specific, single host or network in order to identify which network hop between your machine and the target causes trouble. You can use the following shell script to easily achieve this kind of monitoring.
If the target host is unable to respond to the specified number of ICMP packets, you will get an eMail together with a mtr to see on which hop the problem occurs.

#!/bin/bash

TARGET=8.8.8.8 # Target host or IP address to be monitored.
MAIL_RECIPIENT=you@exam...

Font Combiner offers a way to tweak and adjust any TTF or OTF font (license permitting), by bringing in font glyphs as vector shapes, providing a completely overhauled font generated to the user's specification with alternative metrics options, alternative hinting types, kerning and spacing options and the facility to make any average free font look great.

Examples are here

One of many useful techniques when your test suite needs to talk to a remote API.

If you need to enable NewRelic monitoring on certain machines within the same Rails environment, a simple solution is to utilize the respective hostnames of you machines.

For example, if you have 8 application servers (e.g. app1.example.com, app2.example.com, ...) and want to enable NewRelic on app1 and app2 only, utilize those steps to do so:

1. Put the attached file into your config directory (config/custom_new_relic_configuration.rb).
2. Specify on which hosts NewRelic should be enabled (see NEWRELIC_HOSTS constant and list ...