Cucumber Factory: How to assign polymorphic associations

Cucumber factory supports polymorphic associations out of the box. Just keep in mind that you need to use named associations for this purpose.

class Person < ApplicationModel
  has_many :buildings, inverse_of: :owner

class Company < ApplicationModel
  has_many :buildings, inverse_of: :owner

class Building < ApplicationModel
  belongs_to :owner, optional: true, polymorphic: true


Given there is a customer with the name "Nice customer"
And there is a bui…

Cucumber: How to find unused step definitions

Cucumber has an output format that prints step definitions only. You can use this to find unused ones:

  1. Temporarily add require_relative 'env' to the top of the first file in features/support. --dry-run makes Cucumber skip loading env.rb.
  2. Open a really wide terminal window.
  3. bundle exec cucumber --dry-run --format stepdefs | grep -B1 'NOT MATCHED' --no-group-separator | grep features/step_definitions

This will print all unused step definitions from your project – however, the result will include false positives. Step…

How to upgrade Rails: Workflow advice

When upgrading Rails versions – especially major versions – you will run into a lot of unique issues, depending on the exact version, and depending on your app.

However, it is still possible to give some generic advice on how you want to tackle the update in principle.

How many update steps?

Besides the Rails upgrade itself, you might also want to

  • upgrade your other gems
  • upgrade your Ruby versions

First decide in how many steps you want to run the upgrade. I suggest

  • To do a separate step for each major rails versions. So, if…
Linked contentAuto-destruct in 29 days

Updated: Cucumber: Calling multiple steps from a step definition

  • Added warning that steps will ignore lines not starting with Given/Then/When/And/But.
  • Added contrast example using the step method

How to access before/after pseudo element styles with JavaScript

Accessing pseudo elements via JavaScript or jQuery is often painful/impossible. However, accessing their styles is fairly simple.

Using getComputedStyle

First, find the element in question.

let element = document.querySelector('.my-element') // or $('.my-element').get(0) when using jQuery

Next, use JavaScript's getComputedStyle. It takes an optional 2nd argument to filter for pseudo elements.

let style = window.getComputedStyle(element, '::before')
let color = style.getPropertyValue('background-color…


Understanding database cleaning strategies in tests

TLDR: In tests you need to clean out the database before each example. Use :transaction where possible. Use :deletion for Selenium features or when you have a lot of MyISAM tables.

Understanding database cleaning

You want to clean out your test database after each test, so the next test can start from a blank database. To do so you have three options:

  • Wrap each test in a transaction which is rolled back when you're done (through DatabaseCleaner.strategy = :transaction or `config.use_transactional_fi…
Linked contentRepeats

cucumber_factory 1.14 lets you set array fields, has_many associations, numbers without quotes

Setting array columns

When using PostgreSQL array columns, you can set an array attribute to a value with square brackets:

Given there is a movie with the tags ["comedy", "drama" and "action"]

Setting has_many associations

You can set has_many associations by referring to multiple named records in square brackets:

Given there is a movie with the title "Sunshine"
And there is a movie with the title "Limitles…

Linked contentRepeats

Ruby's percent notation can do more than strings

Percent Notation

We already know that that we can create strings using the percent notation:

%{<foo="bar's ton">} is perfectly fine Ruby.


But there is more. The curly brackets ({}) are interchangable with most unicode characters (e.g. square brackets[]).
Furthermore, you can add a "modifier" to the percent notation to control the return type of th…

Linked contentRepeats

Bash: Build and execute command lines on the fly with "xargs"

xargs is a powerful bash tool that can take input from $STDIN and pass it to a given command. I.e. you can do the following:

$> cat tmp/parallel_cucumber_failures.log

$> cat tmp/parallel_cucumber_failures.log | xargs geordi cucumber
# Running features
> Only: features/authentication.feature:33 features/backend/pages.feature:5 features/backend/pages.feature:60

How to: Run geordi in a single proccess with parallel test setup

Geordi uses parallel_tests if available for running the test suite. To debug an application it is very unhandy to have multiple processes as your terminal I/O will not work as expected once a breakpoint is hit.

Even parallel_tests support an option to enable a single process run, it is not possible to pass this option through geordi. But you can set the number of processes via ENV variable manually:

PARALLEL_TEST_PROCESSORS=1 bundle exec geordi cucu…


When defining methods in specs, you can super into previous definitions

When you def methods in RSpec tests, you can use super to call a method definition that was created in a surrounding describe/context block.


describe User do

  def build_user(attributes = {})

  describe '#my_method' do
    it 'does something' do
      # ...

    context 'when the user has an e-mail address' do
      def build_user(attributes = {})
        super({ email: '' }.merge(attributes))

      it 'd...

Debugging cucumber feature with javascript + firefox vnc

TL;DR Debugging problems with javascript errors in cucumber tests is sometimes easier in the browser. Run the test, stop at the problematic point (with Then pause from Spreewald 1.7+) and open VNC for Firefox.



Raising JavaScript errors in Cucumber scenarios and how to silence them for particular scenarios

Raising JavaScript errors in Cucumber

With selenium JavaScript errors do not cause any failture in your cucumber scenarios. To archive a failture we can use the the Ruby bindings to Selenium Webdriver expose the Webdriver logging API introduced in version 2.38 .

The following step can be used:

Then /^there should be no JavaScript errors$/ do
if alert_present?
# Chrome 54 and/or Chromedriver 2.24 introduced a breaking change on how
# accessing browser logs work.
# Apparently, while an alert/confirm is open, Chro…


Capybara: Find an element that contains a string

There is no CSS selector for matching elements that contains a given string ¹. Luckily, Capybara offers the :text option to go along with your selector:

page.find('div', text: 'Expected content')

You can also pass a regular expression!

page.find('div', text: /Expected contents?/i)

Note that if your CSS selector is as generic as div, you might get a lot more results than you expect. E.g. a <div class="container"> that surrounds your entire layout will probably also contain that text (in a descendant) and Capybara wil…


Geordi: How to rerun failed features

Cucumber will save a file tmp/parallel_cucumber_failures.log will the filenames and line number of the failed scenarios after a full test run.

Normally you can say cucumber -p rerun (rerun is a profile defined by default in config/cucumber.yml) to rerun all failed scenarios. Unfortunately this does not work with geordi yet.

Here is a list of possible workarounds:

geordi firefox bundle exec cucumber -p rerun
cat tmp/parallel_cucucmber_failures.log | xargs geordi cucumber
geordi cucumber `cat…


How to make changes to a Ruby gem (as a Rails developer)

At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (475k downloads), active_type (330k downloads), and geordi (210k downloads) for example (numbers from 2018).

Developing a Ruby gem is different from developing Rails applications, with the biggest difference: there is no Rails. This means:

  • no defined structure (neither for code nor directories)
  • no autoloading of classes, i.e. you need to require all files yourself
  • no [active_support](…

Cucumber features as documentation

Cucumber allows for prose in features and scenarios. Example:

Feature: Cancel account

  There are several ways to cancel a user account. Admins need to 
  do it in complex cases, but normally, users can do it themselves.
  Scenario: User cancels his own account
    Users should be able to cancel an account themselves, so the 
    admins do not need to do it.
    Given a user account for ""
    When I sign in as ""
    And I follow "Cancel account"
    Then I should see "Account canceled"



How to fill in multiple lines in a textarea with cucumber

If you want to fill in textareas with multiple lines of text (containing line breaks) you can use Cucumber's docstrings:

And I fill in "Comment" with:

This is a long comment.
With multiple lines.

And paragraphs.

The step definition is part of the spreewald gem

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