3708 cards

Handling duplicate links with Capybara and Cucumber

Sometimes, you might have duplicate links on a page. Trying to click those links will by default cause Capybara to raise an Ambiguous match error.

If you do not care about which of those links are clicked, you can disable this errors by adding the following meta step:

When(/^(.*) \[allow ambiguous\]$/)do |step_text|
  prior_match_strategy = Capybara.match
  Capybara.match = :first
  Capybara.exact = prior_match_strategy

Use it with

When I follow "a duplicate link" [allow ambiguous]
Linked content

Structuring Rails applications: the Modular Monorepo Monolith

Root Insurance runs their application as a monolithic Rails application – but they've modularized it inside its repository. Here is their approach in summary:


  • Keep all code in a single repository (monorepo)
  • Have a Rails Engine for each logical component instead of writing a single big Rails Application
  • Build database-independent components as gems
  • Thus: gems/ and engines/ directories instead of app/
  • Define a dependency graph of components. It should have few edges.
  • Gems and Engines can be extracted easier once nece…
Linked contentAuto-destruct in 3 days

Updated: Webpack(er): A primer

Added Webpack 4 example to the "Adding images" section

Linked contentAuto-destruct in 3 days

Updated: Migration from the Asset Pipeline to Webpacker

  • Added check for css extraction in webpacker.yml
  • Added link to Webpack(er) A primer
  • Added item 3 and 4 to the Cleanup section
Linked contentRepeats

Taking screenshots in Capybara

Capybara-screenshot can automatically save screenshots and the HTML for failed Capybara tests in Cucumber, RSpec or Minitest.

Requires Capybara-Webkit, Selenium or poltergeist for making screenshots. They're saved into $APPLICATION_ROOT/tmp/capybara

The attached files contain config for cucumber integration and a Then show me a screenshot step.

Including assets for prettier presentation

Make sure to add this to config/environments/test.rb

# Do not generate digests fo…

Linked contentRepeats

Firefox cancels any JavaScript events at a fieldset[disabled]

If you try to listen to events on elements that are nested inside a <fieldset disabled>, Firefox will stop event propagation once the event reaches the fieldset. Chrome and IE/Edge will propagate events.

Since we often bind event listeners to document this can be annoying.

You could solve it by…

Linked contentAuto-destruct in 7 days

CucumberFactory 2.0 released

We just released version 2.0 of CucumberFactory. The major version was increased because of the breaking change below.

2.0.0 - 2020-02-10

Breaking changes

  • CucumberFactory now raises an ArgumentError if some parts of a matched step were not used. For example, while this step was accepted in recent versions, it will now complain with the message Unable to parse attributes " and the ".:

    Given there is a user with the attribute "foo" and the

Compatible changes

Checklist: Using Carrierwave in a Rails project

This checklist should help you to check edge cases that are not part of the default Carrierwave configuration.

Capybara 'fill_in': Ambiguous match for different input names

When you have two inputs, where one contains the name of the other (eg. Name and Name with special treatment), Capybara's fill_in method will fail with the following message:

Ambiguous match, found 2 elements matching visible field "Name" that is not disabled (Capybara::Ambiguous)

You can force Capybara to match exactly what you are typing (which makes your tests better anyways) with match: :prefer_exact:

name = 'Name'
value = 'Bettertest Cucumberbatch'
fill_in(field, with: value, match: :prefer_exact)


Linked contentRepeats

Showing a custom maintenance page while deploying

Add a custom maintenance page for each vhost (require capistrano 3.x):


Add this line to your application's Gemfile:

gem 'capistrano', '~> 3.0'
gem 'capistrano-maintenance', '~> 1.0'

Add this line to you application's Capfile:

require 'capistrano/maintenance'

Enable task

Present a maintenance page to visitors. Disables your application's web interface by writing a #{maintenance_basename}.html file to each web server. The servers must be configured to detect the presence of this file, and if it i…

Linked contentRepeats

CSS: Opacity is not inherited in Internet Explorer

Non-static elements will not inherit their parent's opacity in IE for no good reason. This can lead to unexpected behaviour when you want to fade/hide an element and all its children.

To fix it, give the parent element defining the opacity a non-static positioning. For example:

.parent {
  opacity: 0.2;
  position: relative; /* for IE */

While the linked article describes this problem for IE9 and below, I have encountered the same issue in IE10 and IE11.

Just go away, Internet Explorer!


Rspec: around(:all) and around(:each) hook execution order


  • around(:suite) does not exist.
  • around(:all) runs after before(:all) and before after(:all).
  • around(:each) runs before before(:each) and after after(:each).

As this is not 100% obvious (and not yet documented) it is written down in this card. In RSpec 3 :each has the alias :example and :all the alias :context.


RSpec.configure do |config|
config.before(:suite) { puts 'BEFORE :suite' }
config.after(:suite) { puts 'AFTER :suite' }

describe 'order of hook execution' do


Always convert and strip user-provided images to sRGB

Debugging image color profiles is hard. You can't trust your eyes in this matter, as the image rendering depends on multiple factors. At least the operation system, browser or image viewer software and monitor influence the resulting image colors on your screen.

When we offer our users the possibility to upload images, they will most likely contain tons of EXIF metadata and sometimes exotic color profiles like eciRGB. We want to get rid of the metadata, as it might contain sensitiv…

How to capture a screen-cast on Linux


I recommend simplescreenrecorder, it produces an adequate output with only a few clicks. The audio recording contained some static noises, but that might be caused by my microphone.

Recording only a single screen or fixed rectangle is supported. The video quality seems quite grained when using the default settings - I found that using the MKV container, H.264 codec, "0" constant rate factor and "veryslow" preset results in the best video quality.

If you don't insist on high …

Jasmine: Test that an object is an instance of a given class

To test that an object was constructed by a given constructor function, use jasmine.any(Klass):

describe('plus()', function() {
  it ('returns a number', function() {
    let result = plus(1, 2)

Also see Expecting objects as method invocation arguments.


Defining new elements for your HTML document

Browsers come with a set of built-in elements like <p> or <input>. When we need a new component not covered by that, we often build it from <div> and <span> tags. An alternative is to introduce a new element, like <my-element>.

When a browser encounters an unknown element like <my-element>, the browser will proceed to render <my-element>'s children. The visual rendering of your page will not be affected.

If you care about their HTML being valid, your new element should contain a dash character (-) to mark it as a *custom el…


RSpec: be_true does not actually check if a value is true

Don't use be_true to check if a value is true. It actually checks if it anything other than nil or false. That's why it has been renamed to be_truthy in recent RSpec versions.

The same thing holds for be_false, which actually checks if a value is not "truthy".

If you want to check for true or false in RSpec 2, write this instead:

value.should == true
value.should == false

If you want to check for true or false in RSpec 3+, write this instead:


This website uses cookies to improve usability and analyze traffic.
Accept or learn more