exception_notification: Send exception mails in models

You're using exception_notification and want to send exception mails within a model. Here's how.

The ExceptionNotifier class has a method notify_exception for that. Simply pass an exception:

ExceptionNotifier.notify_exception Exception.new("testfoo")

=> #<Mail::Message:77493640, Multipart: false, Headers: <Date: Mon, 24 Sep 2012 13:37:00 +0200>,
<From: foo@example.com>,
<To: ["fail@failtrain.com", "fail@failbus.org"]>,
<Message-ID: <5060543b3759_212311986a0305e...

Migrating to Spreewald

This describes how to migrate an existing cucumber test suite to Spreewald.

  1. Add the gem

  2. Include spreewald into your cucumber environment by putting
    require 'spreewald/web_steps'
    require 'spreewald/email_steps'
    # ...
    or just
    require 'spreewald/all_steps'
    into your support/env.rb.

  3. Look through your step definitions for everything that might be included in Spreewald. Candidates are web_steps, shared_steps, table_steps, `em...

Using before(:context) / before(:all) in RSpec will cause you lots of trouble unless you know what you are doing

TL;DR Avoid before(:context) (formerly before(:all)), use before(:example) (formerly before(:each)) instead.

If you do use before(:context), you need to know what you are doing and take care of any cleanup yourself.

Why?

Understand this:

  • before(:context) is run when the context/describe block begins,
  • before(:context) is run outside of transactions, so data created here will bleed into other specs
  • before(:example) is run before each spec inside it,

Generally, you'll want a clean setup for each s...

Git basics: checkout vs. reset

Today I got a better understanding of how git works, in particular what git checkout and git reset do.

Git basics

  • A commit holds a certain state of a directory and a pointer to its antecedent commit.
  • A commit is identified by a so-called ref looking something like 7153617ff70e716e229a823cdd205ebb13fa314d.
  • HEAD is a pointer that is always pointing at the commit you are currently working on. Usually, it is pointing to a branch which is pointing to that commit.
  • Branches are nothing but pointers to commits. Y...

Create autocompletion dropdown for Cucumber paths in Textmate

Ever wanted autocompletion for paths from paths.rb in Cucumber? This card lets you write your steps like this:

When I go to path *press tab now* # path is replaced with a list of all known Cucumber paths

This is how you do it

(key shortcuts apply for TextMate2)

  1. Open the bundle editor (ctrl + alt +  + B)

  2. Create a new Item ( + N), select "Command"

  3. Paste this:
    ^
    #!/usr/bin/env ruby -wKU
    require File.join(ENV['TM_SUPPORT_PATH'], 'lib', 'ui.rb')

    cucumber_paths = File.join ENV['TM_PROJECT_DIRECTORY'], 'features'...

Imagemagick: Batch resize images

Trick: Do not use convert but mogrify:

mogrify -resize 50% *

This overwrites the original image file.

In contrast, convert writes to a different image file. Here is an example if you need this:

cd /path/to/image/directory
for i in `ls -1 *jpg`; do convert -resize 50% $i "thumb_$i"; done

How to make your application assets cachable in Rails

Note: Modern Rails has two build pipelines, the asset pipeline (or "Sprockets") and Webpacker. The principles below apply for both, but the examples shown are for Sprockets.


Every page in your application uses many assets, such as images, javascripts and stylesheets. Without your intervention, the browser will request these assets again and again on every request. There is no magic in Rails that gives you automatic caching for assets. In fact, if you haven't been paying attention to this, your application is probabl...

Test meta-refresh redirects with Cucumber

The step definition below allows you to write:

Then I should see an HTML redirect to "http://www.makandracards.com" in the page head

Capybara

Then /^I should see an HTML redirect to "([^\"]*)" in the page head$/ do |redirect_url|
  page.should have_xpath("//meta[@http-equiv=\"refresh\" and contains(@content, \"#{redirect_url}\")]")
end

To find meta tags with Capybara, you can also use page.find('meta', visible: false).

Manage ssh keys with Keychain

Keychain helps you to manage ssh and GPG keys in a convenient and secure manner. It acts as a frontend to ssh-agent and ssh add, but allows you to easily have one long running ssh-agent process per system, rather than the norm of one ssh-agent per login session.

This dramatically reduces the number of times you need to enter your passphrase. With keychain, you only need to enter a passphrase once every time your local machine is rebooted. Keychain also makes it easy for remote cron jobs to securely "hook in" to a long running ssh-agent p...

How to fix gsub on SafeBuffer objects

If you have an html_safe string, you won't be able to call gsub with a block and match reference variables like $1. They will be nil inside the block where you define replacements (as you already know).

This issue applies to both Rails 2 (with rails_xss) as well as Rails 3 applications.

Here is a fix to SafeBuffer#gsub. Note that it will only fix the $1 behavior, not give you a safe string in the end (see below).

Example

def test(input)...

Fun with Ruby: Returning in blocks "overwrites" outside return values

In a nutshell: return statements inside blocks cause a method's return value to change. This is by design (and probably not even new to you, see below) -- but can be a problem, for example for the capture method of Rails.


Consider these methods:

def stuff
  puts 'yielding...'
  yield
  puts 'yielded.'
  true
end

We can call our stuff method with a block to yield. It works like t...

How to test print stylesheets with Cucumber and Capybara

A print stylesheet is easy to create. Choose a font suited for paper, hide some elements, done. Unfortunately print stylesheets often break as the application is developed further, because they are quickly forgotten and nobody bothers to check if their change breaks the print stylesheet.

This card describes how to write a simple Cucumber feature that tests some aspects of a print stylesheets. This way, the requirement of having a print stylesheet is manifested in your tests and cannot be inadvertedly removed from the code. Note that you can...

RSpec and Cucumber: Shorthand syntax to run multiple line numbers in the same file

This works in modern RSpecs (RSpec >= 2.x) and Cucumbers:

rspec spec/models/node_spec.rb:294:322
cucumber features/nodes.feature:543:563:579

Also your features should be shorter than that :)

Disable the Java plugin in browsers to avoid drive-by attacks

Every now and then, Java is subject to security issues where code can break out of Java's sandbox and obtain more privileges than it should.
In almost all cases, such issues are actively being used for drive-by attacks via the Java browser plug-in, for example by malicious ad banners.

Since removing Java completely is not an option for us, make sure the Java plug-in is always disabled in every browser, even when you have updated Java on your machine.
Please re...

How to inspect controller filter chains in specs

Sometimes you need to look at the filter chain in specs. You can do it like that on Rails 2:

controller.class.filter_chain.map(&:method)

Note that we need to look at the controller's class since before_filter and after_filter stuff happens on the class level.

Also mind that the above code will give you all filters, both those run before and after an action. You can query before? and after? on the filter objects to scope down to only some of them:

controller.class.filter_chain.select(&:before?).map(&:method)

For Rails 3, ...

Rspec shared example group error: ensure_shared_example_group_name_not_taken

Never name your shared example group *_spec.rb. Otherwise rspec will try to load your example group as a spec and you will get the error above.

Limitations you should be aware of when Internet Explorer 9 parses CSS files

Internet Explorer until version 9 has some limitations when parsing CSS files

Summarized, these are:

  • Up to 31 CSS files or <style> tags per page.
  • Up to 4095 selectors per CSS file.
  • Up to 3 nested @import rules

To test the selector limit for a specific browser, check this CSS selector limitation test website.

When you run into this issue, the following links might be helpful to fix the problem. The Idea is to split up the css ...

Mock the browser time or time zone in Selenium features

In Selenium features the server and client are running in separate processes. Therefore, when mocking time with a tool like Timecop, the browser controlled by Selenium will still see the unmocked system time.

timemachine.js allows you to mock the client's time by monkey-patching into Javascript core classes. We use timemachine.js in combination with the Timecop gem to synchronize the local browser time to the ...

Why stubbing on associated records does not always work as expected

Be careful when stubbing out attributes on records that are defined by associations. Nothing is as it seems to be.

The associated record has its own universe of things; when delegating calls to it, you ca not stub methods on the associated record and expect them to be around. That is a general issue with this pattern/approach.

What's happening?

Consider these classes:

class Post < ActiveRecord::Base
  belongs_to :thread
  
  def thread_title
    thread.title
  end
end

class Thread < Acti...

Test your CSS rendering output with GreenOnion

No one wants to cry over regression issues in views; does testing HTML and CSS have to be such a back and forth between designers and devs? Why is it that the rest of the stack can have TDD and BDD but not the presentation layer? Well, GreenOnion is here to help you get the same results on testing front-end styling that you've enjoyed in your unit and integration tests up to now.
GreenOnion records 'skins', which are snapshots of the current state of a view (or any page that a browser can navigate to). The first time that it is run on a view...

rspec_candy 0.2.0 now comes with our most popular matchers

Our rspec_candy gem now gives you three matchers:

be_same_number_as

Tests if the given number is the "same" as the receiving number, regardless of whether you're comparing Fixnums (integers), Floats and BigDecimals:

100.should be_same_number_as(100.0)
50.4.should be_same_number_as(BigDecimal('50.4'))

Note that "same" means "same for your purposes". Internally the matcher compares normalized results of #to_s.

be_same_second_as

...

Gem development: When your specs don't see dependencies from your Gemfile

When you develop a gem and you have a Gemfile in your project directory, you might be surprised that your gem dependencies aren't already required in your specs. Here is some info that should help you out:

  • Bundler actually doesn't automatically require anything. You need to call Bundler.require(:default, :your_custom_group1, ...) for that. The reason why you never had to write this line is that Rails does this for you when it boots the environment.
  • That also means that if you have an embedded Rails app in your spec folder (like [h...

Consul 0.4.0 released

Consul 0.4.0 comes with some new features.

Dependencies

  • Consul no longer requires assignable_values, it's optional for when you want to use the authorize_values_for macro.
  • Consul no longer uses ActiveSupport::Memoizable because that's deprecated in newer Railses. Consul now uses Memoizer for this.

Temporarily change the current power

When you set Power.current to a power in an RS...

Check if an object is an ActiveRecord scope

Don't say is_a?(ActiveRecord::NamedScope::Scope) because that is no longer true in Rails 3 and also doesn't match unscoped ActiveRecord classes themselves (which we consider scopes for all practical purposes).

A good way is to say this instead:

object.respond_to?(:scoped)