Change the timestamp of a file in Ruby

This is somewhat similar to the touch command of Linux:

FileUtils.touch 'example.txt', :mtime => Time.now - 2.hours

If you omit the :mtime the modification timestamp will be set to the current time:

FileUtils.touch 'example.txt'

You may also pass an array of filenames:

FileUtils.touch %w[ foo bar baz ], :mtime => Time.now - 2.hours

Non-existent files will be created.

Force Google Chrome to run in English on Linux

If you need Google Chrome to run in English, and your system locale is a non-English one, you have two options:

  • Switch your system to an English locale
  • Head over to /opt/google/chrome/locales/ and remove any .pak files except those starting with “en”. They reappear when Chrome gets updated.

This may help you running your Selenium tests using the Chrome driver on applications that choose the language from what the browser sends as preferred language (which Chrome guesses from your system locale).

What to do when Google only syncs some of your contacts

When some of your Google contacts are no longer synchronized with your e-mail client or mobile phone, those contacts are not in a group "My Contacts". Google only syncs contacts in that group.

In order to fix this:

  • Open Google Contacts
  • Select all contacts (there's a link)
  • Press "Move to My Contacts"

Note that when you are using Mozilla Thunderbird with the Google Contacts add-on, Thunderbird won't add new contacts into the "My Co...

How to fix: undefined method `specifications' (caused by RubyGems 1.8)

Sometimes, when running a rake task, RubyGems 1.8.5 raises an error:

rake aborted!
undefined method `specifications' for "/usr/lib/ruby/gems/1.8":String

This has been fixed since May 31 but is still not available as a new RubyGems version.

Either wait for a new version to eventually come out, downgrade to some really old version (1.6.2 works for some) or apply the fix manually:

  • Find your rubygems.rb -- mine was located at `/usr/local/lib/sit...

RubyMine crashes Ubuntu 11.04 window decorator on exit

My RubyMine (and it seems like many other Java GUI applications) crashes the Compiz window decorator almost every time on exit. This also seems to happen for the Unity decorator.

Update: The commited fix from below seems to have made it into the stable Ubuntu repository.

Easy mode

You can restore window decorations by executing this command:

gtk-window-decorator --replace &

This is only a temporary fix.

Hard mode

Also, there is a committed fix that is n...

How to use helper methods inside a model

Simple

If you want to use a helper_method my_helper_method inside a model, you can write

ApplicationController.helpers.my_helper_method

When using multiple helpers

delegate :helpers, to: ApplicationController
helpers.my_helper_method
helpers.my_other_helper-method

More flexible

If you need a bit more flexibility, for example if you also need to override some methods, you can do this:

class HelperProxy < ActionView::Base
  include ApplicationController.master_helper_modu...

Using RSpec's late resolving of "let" variables for cleaner specs

Consider the following:

describe '#something' do
  context 'with lots of required arguments' do
    it 'should work' do
      subject.something(:foo => 'foo', :bar => 'bar', :baz => 'baz').should == 'Hello world'
    end

    it 'should work again' do
      subject.stub :target => 'universe'
      subject.something(:foo => 'foo', :bar => 'bar', :baz => 'baz').should == 'Hello universe'
    end

    it 'should work yet again' do
      subject.stub :target => 'multiverse'
      subject.something...

Helpers to render (money) amounts

When rendering a number, you want to pretty up the string coming from #to_s:

  • Render 0.0 as 0
  • Sometimes require a minimum number of digits after the decimal separator
  • Change the decimal separator from . to , in some European countries
  • Render a dash if the given amount is nil

The attached helper that does just that. Some usage examples with their resulting strings:

Invocation Result
amount(0) 0
amount(0.0) 0
amount(0.5) 0,5
amount(1.5, :minimum_precision => 2) 1,50
`amo...

Why developers should be force-fed state machines

Most web applications contain several examples of state machines, including accounts and subscriptions, invoices, orders, blog posts, and many more. The problem is that you might not necessarily think of them as state machines while designing your application. Therefore, it is good to have some indicators to recognize them early on. The easiest way is to look at your data model.

Order in which RSpec processes .rb files

Because your examples should not change global state, you should not need to care about the order in which RSpec processes your .rb files. However, in some cases you might want to know.

RSpec 3

  • Runs .rb files in alphabetical order of their file paths by default (or when you specify --order defined).
  • You run t...

Stubbed class methods in RSpec 1 remain stubbed in other examples

I encountered a bug in RSpec 1.x where stubbed class methods ("static methods") would not be unstubbed before the next example, causing it to fail. This behavior can come and go as you edit your specs, since this can change the order in which RSpec evaluates your .rb files.

I was not able to find a fix for this behavior. Calling #rspec_reset und #unstub!(:method) on the class after the example did not help. I know for sure that stubbing static methods has not been a problem in many other projects. I encountered the bug while working o...

New Cucumber Factory makes it easier to associate records

I pushed a new version of the Cucumber Factory gem. This new release lets you refer to a previously created record by any string attribute:

Given there is a movie with the title "Before Sunrise"
And there is a movie with the title "Limitless"
And there is a movie with the prequel "Before Sunrise"

Note how we didn't have to explicitly give the prequel a name in the example above. This is still possible, but will rarely be necessary now:

Given "Before Sunrise" is a movie with...

Example .ssh/config file

Attached you can find an example ~/.ssh/config file which makes working with SSH more pleasant. It contains several tweaks:

After you download the file to ~/.ssh/config, edit the file in a text editor to tailor it to your individual needs.

A nicer way to run RSpec and/or Cucumber

geordi, our collection of awesome shell scripts, has been extended by three scripts to help you call RSpec or Cucumber:

cuc

This script runs Cucumber the way you want it:

  • Prints some line feeds to easily find your test results when you come back to the console later
  • Configures Cucumber to use cucumber_spinner if it is available in your Gemfile
  • Runs Cucumber under bundle exec
  • Uses an old version of Firefox for Selenium (Javascript) features...

Merging two arbitrary ActiveRecord scopes

(Rails has a method ActiveRecord::Relation#merge that can merge ActiveRecord scopes. However, its behavior has never been clear, and in Rails 7 it still discards conditions on the same column by the last condition. We discourage using #merge!)

The best way to merge ActiveRecord scopes is using a subquery:

scope_a.where(id: scope_b)

It is a little less concise than #merge, but unambiguous.

Example

Assume a model where a deal has many documents:

class Deal < ApplicationRecord
  has_many :...

List directories ordered by size (with human-readable output)

You know there is the du command to fetch the disk usage of a directory (“.” in this example). By default, output is sorted by directory name, not size:

du -h --max-depth=1 .
40K  ./a
2.3G ./b
3.1M ./c
500M ./d
2.8G .

To see which directories take up the most (or least) space you can order them by size like this (the -h switch does the magic of understanding humanized size formats):

du -h --max-depth=1 . | sort -h
40K  ./a
3.1M ./c
500M ./d
2.3G ./b
2.8G .

Note that you will need to...

How to test resource_controller hooks

When using the resource_controller gem you often hook onto events like this:
update.before do
do_something
end

For testing such things in your controller you should -- as always -- not trigger something that eventually calls the thing you want.\
Instead, in your specs, have resource_controller run those hooks like it does itself. Like that:

describe 'before update' do
 ...

SSL: Build a Certificate signing request (CSR)

In order to request a SSL certificate from any dealer, you usually need a CSR certificate. As both the CSR as well as key are created in this step, make sure you save this certificate on a trusted, secure machine only. Usually this is your production environment.

Run this on the server (not on your machine) as root.\
Replace your-domain.tld with the domain you request the certificate for and YYYY with the current year so you will not have any conflicts when requesting a certificate next year.

openssl req -new -sha256 -out www.your-dom...

Soft-scroll to an anchor with jQuery

This snippet makes links that refer to an anchor (like "<a href="#something">...</a>") scroll softly to it.\
In this example we only do it for links that also own a data-animate attribute.

$('a[href^="#"][data-animate]').live('click', function() {
  var hash = $(this).attr('href');
  var offset = $(hash).offset();
  if (offset) {
    $('html, body').animate({ scrollTop: offset.top }, 'slow');
    location.hash = hash;
    return false;
  }
});

Note that this could basically work for any element whos...

Semantic markup standard for search engines

If you would like to enrich your website with semantic markup like contact data, places or events you should have a look at schema.org. "Search engines including Bing, Google and Yahoo! rely on this markup to improve the display of search results, making it easier for people to find the right web pages."

The following example from the schema.org documentation shows you how to describe a movie with semantic markup:

<div itemscope itemtype ="http://schema.org/Movie">
  <h1 itemp...

Matching elements on complex web pages with Webrat

XPath matchers can be combined with CSS-selector matchers. This is really useful if not, for example, the content of an element should be matched but the element itself like in the following example. Here a form is used to display data as default value in its input elements. This can be the case in web applications in which data should be edited easily without additional clicks.

Execution of shell code in Ruby scripts

Deprecated ways to execute shell code in Ruby

This is just a reference for legacy code. For new code, always use capture3.

%x{ } or backticks – quick and easy

Returns the standard output of running the given command in a subshell. This is an alias for `...`, and you can use string interpolation.

Example:

name = 'ls'
result = `which #{name}`

It does not escape anything you inject in the string, so be aware of possible security vulnerabilities...

Defining host aliases in your SSH config

You probably already manage servers you often connect to inside the ~/.ssh/config file. What is nice: you may define alias names for hosts so that you can say something like ssh foobar-staging.

This is especially helpful for servers whose hostnames are hard to remember or who don't have a DNS record at all (and must be accessed via their IP address).

To achieve the above, you can define something like this in your ~/.ssh/config:

Host foobar-staging
  Hostname staging.example.com

Note that SSH will only match this for `ssh f...

How to employ and run your tests with parallel_tests to speed up test execution

When your cucumber features grow massively over time, the test execution can take a lot of time.
One easy way to speed up your test execution is to use the parallel_tests gem.
It comes along with some useful rake tasks that let you setup your local test environment shortly to run your features, specs or unit-tests in parallel.

Follow these steps to get it to work.

  1. Add the parallel_tests gem to your Gemfile test sections like that:

    # ./Gemfile
    
    group :development, :test do
    

...