grosser/parallel

Ruby has Enumerable.find(&block), which returns the first item in the collection for which the block evaluates to true.

first_post_with_image = posts.find do |post|
  post.image
end

However, sometimes it's not the item you're int...

If rspec hangs with no output and you dont get a backtrace neither with --backtrace nor by just killing it with crtl-c,
you can put the following in your spec/spec_helper.rb:

puts "rspec pid: #{Process.pid}"

trap 'USR1' do
  thread...

As a developer you may have many tools watching your project for changes: Your IDE, Webpack, Guard, etc. This is often done with an inotify watcher. If you have too many inotify instances you may run into limits of your operating system.

To fin...

When you accept a table in your Cucumber step definition, that table object will have the cryptic type Cucumber::Ast::Table. Don't immediately call `table...

Ruby's private keyword might do a lot less than you think.

"private" does not apply to class methods defined on self

This does not make anything private:

class Foo

  priva...

TLDR: This card explains which threads and processes interact with each other when you run a Selenium test with Capybara. This will help you understand "impossible" behavior of your tests.

When you run a Rack::Te...

Remember why preloading associations "randomly" uses joined tables or multiple queries?

If you don't like the cleverness of thi...

Occasionally you need to do something directly on the server -- like having all records recalculate something that cannot be done in a migration because it takes a long time.

Let's say you do something like this:

Project.all.each(&:recal...

There are many different methods that allow mapping an Array to a Hash in Ruby.

Array#to_h with a block (Ruby 2.6+)

You can call an array with a block that is called with each element. The block must return a [key, value] tuple.

This i...

When you have a hex color code, you can easily convert it into its RGB values using plain Ruby.

>> "#ff8000".match(/^#(..)(..)(..)$/).captures.map(&:hex)
=> [255, 128, 0]

You can use that to implement a simple "hex to CSS rgba value ...