When you are using lambdas in RSpec to assert certain changes of a call, you know this syntax:

expect { playlist.destroy }.to change { Playlist.count }.by(-1)

While you can define multiple assertions through multiple specs, you may not want to do so, e.g. for performance or for the sake of mental overhead.

Multiple expectations on the same subject

RSpec allows chaining expectations simply by using and.

expect { playlist.destroy }
  .to change { Playlist.count }.by(-1)
  .and not_change { Video.count }

...

Given you have an array column like this:

create_table "users", force: :cascade do |t|
  t.integer "movie_ids", default: [], array: true
end

You might think that the following queries yield the same result:

User.where(movie_ids: [16, 17])
User.where(movie_ids: [17, 16])

Turn's out - they are not! They do care about array ordering more than I do.

To query for identical arrays independent of their order you have to either:

1. Sort both the query and database content. If you're on Rails 7.1 you can use the new [`normal...

I recently stumbled over a problem that my feature tests broke in CI because of a mismatching chromedriver version.

In this specific project we have a fixed Chromium version in a Debian 12 environment instead of Chrome. The tests however used a recent chrome version instead.

$ chromedriver --version
ChromeDriver 117.0.5938.149 (e3344ddefa12e60436fa28c81cf207c1afb4d0a9-refs/branch-heads/5938@{#1539})
$ chromium --version
Chromium 117.0.5938.149 built on Debian 12.1, running on Debian 12.1

> WARN Selenium [:selenium_manager] The chromed...

Or: How to avoid and refactor spaghetti code

Please note that I tried to keep the examples small. The effects of the methods in this card are of course much more significant with real / more complex code.

What are the benefits of more modular code?

Code is written once but read often (by your future self and other developers who have to understand it in order to make changes for example). With more modular code you reduce the scope of what has to be understood in order to change something. Also, naming things gives you the opportunity t...

Mobile Chrome and Safari support the "web share API" which allow you to use the native share functionality of an Android or iOS phone. Some desktop OSs like Windows or MacOS also support native share dialogs. See Can I Use for a detailed support matrix.

When clicking a share button using this API, the browser will automatically show all installed applications that support content sharing, such as Whatsapp, Facebook, Twitter, e-mail etc.

The API is extremely simple to use:

if ...

There are two ways to lock a user in devise.

1. Using the lockable module
2. Customizing the user account status validation when logging in.

It depends on your requirements which methods works best.

Locking a user on soft delete

We recommend to use option 2 when you want to couple the lock to the m...

Any form fields where users enter numbers should be an <input type="number">.

Numeric inputs have several benefits over <input type="text">:

• On mobile or tablet devices, number fields show a special virtual keyboard that shows mostly digit buttons.
• Decimal values will be formatted using the user's language settings.
  For example, German users will see 1,23 for <input type="number" value="1.23">.
• Values in the JavaScript API or when submitting forms to the server will always use a point as decimal separator (i.e. "1.23" eve...

Example

87.140.79.42 - - [23/Jan/2024:09:00:46 +0100] "GET /monitoring/pings/ HTTP/1.1" 200 814 "-" "Ruby"
87.140.79.42 - - [23/Jan/2024:09:00:46 +0100] "GET /monitoring/pings/ HTTP/1.1" 200 814 "-" "Ruby"
87.140.79.41 - - [23/Jan/2024:09:00:46 +0100] "GET /monitoring/pings/ HTTP/1.1" 200 814 "-" "Ruby"
87.140.79.42 - - [23/Jan/2024:09:00:46 +0100] "GET /monitoring/pings/ HTTP/1.1" 200 814 "-" "Ruby"

Goal

Count and sort the number of requests for a single IP address.

Bash Command

awk '{ print $1}' test.log | sort...

Sometimes you want to fetch associations for an ActiveRecord that you already loaded, e.g. when it has deeply nested associations.

Edge Rider gives your models a static method preload_associations. The method can be used to preload associations for loaded objects like this:

class UsersController < ApplicationController
  def show
    @user = User.find(params[:id])
    @user.preload_associations(threads: { posts: :author }, messages: :sender)
  end
end

The attached initializers re...

You can share a state in Ruby with global variables. Even if you should avoid them whenever possible, for debugging an application this could be temporary quite handy.

Example:

class User

  after_save { byebug if $debug; nil }

  def lock
   self.locked = true
   save
  end

end

Rspec.describe User do

  let(:user) { create(:user) } 

  before do
   # Many users are created and saved in this hook, but we don't want the debugger to stop for them...

When your model is using a callback like before_save or before_validation to calculate an aggregated value from its children, it needs to skip those children that are #marked_for_destruction?. Otherwise you will include children that have been ticked for deletion in a nested form.

Wrong way

class Invoice < ApplicationRecord
  has_many :invoice_items
  accepts_nested_attributes_for :invoice_items, :allow_destroy => true # the critical code 1/2
  before_save :calculate_and_store_amount                              # the crit...

So you are comparing two Time objects in an RSpec example, and they are not equal, although they look equal:

expected: Tue May 01 21:59:59 UTC 2007,
     got: Tue May 01 21:59:59 UTC 2007 (using ==)

The reason for this is that Time actually tracks fractions of a second, although #to_s doesn't say so and even though you probably only care about seconds. This means that two consecutive calls of Time.now probably return two inequal values.

Consider freezing time in your tests so it is not dependent on the speed of the executi...

I encountered a unlucky behavior of byebug 11.1.3 (the most recent version at time of writing) when using it with Rails 6 and it's new autoloading component, zeitwerk. There already is a issue for that, so I hope it will be fixed with a future release.

The following test succeeds:

  context 'factories' do
    let(:test_case) { FactoryBot.create(:test_case) }
    it 'are valid' do
      expect(test_case).to be_valid
    end
  end

But when I did the same in byebug the foll...

Ruby has the class Rational which allows you to store exact fractions. Any calculation on these variables will now use fractional calculations internally, until you convert the result to another data type or do a calculation which requires an implicit conversion.

Example use case:

Lets say you want to store the conversion factor from MJ to kWh in a variable, which is 1/3.6. Using BigDecimals for this seems like a good idea, it usually helps with rounding errors over a float, but the...

When you mocked method calls in RSpec, they are mocked until the end of a spec, or until you explicitly release them.

You can use RSpec::Mocks.with_temporary_scope to have all mocks applied inside a block to be released when the block ends.
Example:

RSpec::Mocks.with_temporary_scope do
  allow(Rails).to receive(:env).and_return('production'.inquiry)
  puts Rails.env # prints "production"
end
puts Rails.env # prints "test"

Note that, when overriding pre-existing mocks inside the block, they are not reverted to the previously ...

Note

Don't use reruns as a mean to work around flaky tests. You should always try to fix those instead of rerunning them regularly.

Setup

Configure RSpec to persist the result of your test runs to a file. This is necessary to be able to rerun examples.
Add this to your spec/spec_helper.rb :

  config.example_status_persistence_file_path = 'spec/examples.txt'

Rerun all failed examples using --only-failures

bundle exec rspec --only-failures (or `...

tl;dr

Don't forget require 'English' if you use a named global such as $LAST_MATCH_INFO. Otherwise this could result in an annoying bug.

With Ruby's build-in library English you can reference global variables with an english name. This makes you code easier to read and is also suggested by Rubocop's Style/GlobalVars cop.

Example before:

if 'foo' =~ /foo/
  puts $~[1] # => foo
end

Example af...

When your application is open for public sign up and sends out transactional e-mails to a large number of users, e-mail deliverability becomes an issue.

E-mail providers work hard to eliminate spam and have put in place relatively tight checks what kinds of emails they will accept, and from whom. To that end we use tools like mail-tester.com to make our mails as acceptable as possible. Unfortunately, there will always be providers that reject our e-mails for some reason or other, sometimes outside of our control.

For exa...

By activating strict_loading you force developers to address n+1 queries by preloading all associations used in the index view. Using an association that is not preloaded will raise an ActiveRecord::StrictLoadingViolationError.

I think it's a good default to activate strict_loading in your controllers' #index actions. This way, when a change introduces an n+1 query, you...

Use rules to include or exclude jobs in pipelines.

Rules are evaluated in order until the first match. When a match is found, the job is either included or excluded from the pipeline, depending on the configuration. The job can also have certain attributes added to it.

rules replaces only/except and they can’t be used together in the same job. If you configure one job to use both keywords, the linter returns a key may not be used with rules error.

GitLab 12.3 introduced rules. You can use them in your .gitlab-ci.yml in your proj...

The Truemail gem (not to be confused with truemail.io) allows validating email addresses, e.g. when users enter them into a sign-up form. It runs inside your application and does not depend on an external SaaS service.

Truemail supports different validation "layers":

1. Regex validation: if the given address is syntactically valid
2. DNS validation (called MX validation): if the given domain exists and can receive email
3. SMTP validation: connects to the host received from DNS and starts a test d...

Applications often show or hide elements based on viewport dimensions, or may have components that behave differently (like mobile vs desktop navigation menus).
Since you want your integration tests to behave consistently, you want to set a specific size for your tests' browser windows.

Using WebDriver options / Chrome device metrics

For Google Chrome, the preferred way is setting "device metrics". This allows you to configure dimensions larger than your display and enable/disable touch behavior.

Simply use register_driver to set up...

In the Gitlab settings the flag Auto-cancel redundant pipelines is enabled by default. This auto-cancels jobs that have the interruptible setting set to true (defaults to false e.g. to not cancel deploys by accident).

Consider to set the interruptible flag for test jobs to reduce the load on your runners like in the following example .gitlab-ci.yml:

rubocop:
  interruptible: true
  script:
    - 'bundle exec rubocop'

rspec:
  int...

If you need a sample video with certain properties for a test you can create one using ffmpeg.
You might want a very low bitrate file to speed up processing in your test. (e.g. you only care about the length, then you can create a video with a very low resolution and framerate)

Create a 21s video with 1fps and 10x10 resolution:
ffmpeg -t 21 -s 10x10 -r 1 -f rawvideo -pix_fmt rgb24 -i /dev/zero sample_21_seconds.mp4