When using Sidekiq in your application, you must write thread-safe code.

This wiki page also lists gems that are known to be unsafe on threaded applications.
When adding a gem that will also be used by a Sidekiq worker, make sure to confirm it's thread-safe.

I often see the use of || to set a default value for a variable that might be nil, null or undefined.

x = x || 'default-value'

This pattern should be avoided in all languages.

While using || works as intended when x is null or an actual object, it also sets the default value for other falsy values, such as false. false is a non-blank value that you never want to override with a default.

To make it worse, languages like JavaScript or Perl have [many more fal...

Proxy caching is a good feature to serve your publicly visible application content faster and reduce load on your servers. It is e.g. available in nginx, but also affects proxies delivered by ISPs.

Unfortunately, there is a little problem in Rails < 6.1 when delivering responses for different MIME-types. Say you have an arbitrary route in your Rails application that is able to respond with regular HTML and JSON. By sending the specific MIME type in the Accept header, you tell the application to either return HTML (text/html) or JSON (`t...

To reverse lookup a fixture by its table name and id, use the following approach on ActiveRecord::FixtureSet:

table = 'users'       # Specify the fixture table name
id = 123122           # Specify the ID to look for

# Find the fixture that matches the given ID
ActiveRecord::FixtureSet.all_loaded_fixtures[table].fixtures.find { |key, value| value['id'] == id }

Result Example:

[
  "one", # Fixture name
  #<ActiveRecord::Fixture:0x00007e79990234c8>, # ActiveRecord::Fixture object
  @fixture= { ... }, # The raw fixtu...

I tried to make it easier to read how to set the sass options for the different build tools.

Updated for selenium-webdriver 4.27 which requires options.add_option(:page_load_strategy, 'none').

Your package-lock.json should always match and resolve all packages from your package.json.
Coming from Yarn, I was looking for an option like Yarn's --frozen-lockfile which validates that. Here is what seems to be the way to do it.

Using npm clean-install

Running npm clean-install instead of npm install will actually validate that your package-lock.json matches your package.json.

You can use npm ci as a shortcut for npm clean-install.

Combine with a cache

The idea of a "clean install" is that it always install...

Warning

safe_constantize is not safe for unfiltered user input

In Rails, the safe_constantize method is a powerful tool that helps developers safely convert strings into constants. This feature is particularly useful in scenarios where constant lookup might fail or could potentially introduce security risks. Let’s dive into what safe_constantize is, how it works, and why you should use it.

What Is safe_constantize?

The `safe_cons...

In development, we store files using ActiveStorage's disk service. This means that stored files are served by your Rails application, and every request to a file results in (at least!) one non-trivial log entry which can be annoying. Here is how to disable those log entries.

Example

Here is an example of what loading a single <img> in an example application writes to the Rails log.

Started GET "/rails/active_storage/blobs/redirect/..." for ::1 at ...
Processing by ActiveStorage::Blobs::RedirectController#show as SVG
  Parameter...

If you update Selenium regularly, you'll run into deprecation warnings similar to:

WARN Selenium [:clear_local_storage] [DEPRECATION] clear_local_storage is deprecated and will be removed in a future release

You can ignore this deprecation warning and clean your logs with logfilters:

Selenium::WebDriver.logger.ignore(:clear_local_storage)

Just specify the tag (:clear_local_storage) you want to ignore.

When you have a string containing umlauts which don't behave as expected (are not matched with a regexp, can't be found with an SQL query, do not print correctly on LaTeX documents, etc), you may be encountering umlauts which are not actually umlaut characters.

They look, depending on the font, like their "real" umlaut counterpart:

• ä ↔ ä
• ö ↔ ö
• ü ↔ ü

However, they are not the same:

'ä' == 'ä' # false
'ä'.size # 1
'ä'.size # 2

Looking at how those strings are constructed reveals what is going on:

'ä'.unpack('U*...

Rails migrations allow you to use a change method whose calls are automatically inverted for the down path. However, if you need to some path-specific logic (like SQL UPDATE statements) you can not define up and down methods at the same time.

If you were to define define all 3 of them, Rails would only run change and ignore up and down. However, Rails 4+ features a helper method called reversible:

class MyMigration < ActiveRecord::Migration

  def cha...

RubyMine allows bookmarking lines of code. This is super-helpful when working on a complex problem.
I've been using this feature for a few years now, and so should you! :)

Here are the default Linux/Windows keystrokes. See the documentation for other keybindings.

Add an anonymous bookmark

F11

A gray checkmark will be shown in the gutter on the left.
If you press F11 again on a bookmarked line, the bookmark will be removed.

Add a named bookmark ("mnemonic")

Ctrl ...

tl;dr

When a cookie includes an Expires attribute or an HTTP response includes caching headers like Expires or Cache-Control, their validity depends on the server's Date header if present. Otherwise, the browser uses its local time. This can lead to issues in tests with mocked time or inconsistent cache behavior.

Cookie Expires depends on the Date header or browser time

When a cookie includes an Expires attribute, the browser evaluates the expiration date relative to a reference time:

1. If the HTTP response ...

In FactoryBot factories, Rails' file_fixture is not available by default. To enable it, include a support module from rspec-rails:

FactoryBot::SyntaxRunner.include(RSpec::Rails::FileFixtureSupport)

That includes ActiveSupport::Testing::FileFixtures, where file_fixture is defined, but also configures the file_fixture_path so that you can actually use file_fixture.

Team C enabled support for description lists in makandracards.
Please make sure to add a newline before the definition starting with colon (:).

Usage example:

Apple

: A fruit that grows on trees.

Orange

: A citrus fruit known for its vitamin C content.

  More details in second paragraph.

will result in:

Apple

A fruit that grows on trees.

Orange

A citrus fruit known for its vitamin C content.

More details in second paragraph.

Updated for Rails 7.2 and Redis 5.

Updated most aspects of this card.

When you find yourself in the situation that you would like to define a custom matcher in your specs, but you do not want to define a global matcher since you need it only for your specific test, there are two ways to do it:

Custom matcher for a single group

If you're only going to include a matcher once, you can also use the matcher macro within an example group:

describe "group" do
  
  matcher :be_just_like do |expected|
    match {|ac...

Sometimes huge refactorings or refactoring of core concepts of your application are necessary for being able to meet new requirements or to keep your application maintainable on the long run. Here are some thoughts about how to approach such challenges.

Break it down

Try to break your refactoring down in different parts. Try to make tests green for each part of your refactoring as soon as possible and only move to the next big part if your tests are fixed. It's not a good idea to work for weeks or months and wait for all puzzle pieces ...

Please don't simply copy line number links from Github. The URL usually contains a branch name like master which will change over time:

https://github.com/makandra/upjs/blob/master/lib/assets/javascripts/up/link.js.coffee#L76

If someone now posts an insertion or deletion to that file into master your link points to the wrong line!

A better way is to press the Y key after clicking on a line number. This will transform the URL to another URL that points to the particular commit:

https://github.com/makandra/upjs/blob/b3b14...

Some key highlights and points from the linked article TestProf II: Factory therapy for your Ruby tests.

The Problem with Factories in Ruby Tests

• Factories are used to easily generate test data.
• However, they can unintentionally slow down test suites by creating unnecessary or excessive associated data (factory cascades).

Understanding Factory-Induced Slowdowns

• Factories often create additional data (e.g., associated records) th...

Rails slightly changed the fragment cache implementation from Rails 7.0 to Rails 7.1. Unfortunately, this is incompatible with how Haml 5 patches Action View buffers. I tried turning a String buffer into an ActionView::OutputBuffer, but this brought up...