Bundle exec for isolated execution in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Ruby code using bundle exec?

Consider you have a Gemfile specifying gem 'colorize', version '0.8.1'. You run the following Ruby script with bundle exec ruby script.rb:

Ruby

require 'colorize'
puts 'Hello'.colorize(:red)

A Raises LoadError because colorize gem is not found

B Prints 'Hello' without color

C Prints 'Hello' in red color in the terminal

D SyntaxError due to incorrect gem usage

💡 Hint

Using bundle exec ensures gems from Gemfile are loaded correctly.

Using bundle exec runs the script with the gems specified in the Gemfile, so 'colorize' gem version 0.8.1 is loaded and the string prints in red.

🧠 Conceptual

intermediate

Why use bundle exec when running Ruby scripts?

Choose the best reason why bundle exec is used before running Ruby commands.

A To run the command with gems specified in the Gemfile, avoiding conflicts with system gems

B To speed up Ruby script execution by caching gems

C To run the script without loading any gems

D To automatically update all gems before running the script

💡 Hint

Think about gem versions and conflicts.

bundle exec runs commands using the gems and versions locked in the Gemfile.lock, preventing conflicts with other installed gems.

🔧 Debug

advanced

What error occurs when running a Ruby script without bundle exec?

Given a project with a Gemfile specifying 'nokogiri' version 1.12.5, running ruby script.rb (without bundle exec) causes an error. What is the most likely error?

Ruby

require 'nokogiri'
puts Nokogiri::VERSION

A SyntaxError: unexpected end-of-input

B RuntimeError: gem version mismatch

C NoMethodError: undefined method 'VERSION' for Nokogiri:Module

D LoadError: cannot load such file -- nokogiri

💡 Hint

Without bundle exec, Ruby might not find the gem installed for this project.

Without bundle exec, Ruby uses system gems which may not include the required version or gem, causing LoadError.

📝 Syntax

advanced

Which command correctly runs a Rake task using bundle exec?

You want to run the Rake task named 'db:migrate' using bundle exec. Which command is correct?

A bundle exec rake db:migrate

B rake bundle exec db:migrate

C bundle rake exec db:migrate

D exec bundle rake db:migrate

💡 Hint

bundle exec should come before the command you want to run.

The correct syntax is 'bundle exec' followed by the command and its arguments.

🚀 Application

expert

How many gems are loaded when running bundle exec ruby script.rb with this Gemfile?

Given this Gemfile content:

source 'https://rubygems.org'
gem 'rails', '7.0.4'
gem 'puma', '~> 5.0'
gem 'nokogiri', '1.12.5'

And bundle install was run successfully. How many gems (including dependencies) are loaded when running bundle exec ruby script.rb?

A Exactly 3 gems only

B Only the gems explicitly required in script.rb

C At least 3 gems plus all their dependencies

D No gems are loaded automatically

💡 Hint

Bundler sets up the environment but does not automatically load (require) the gems; only those required in the script are loaded.

`bundle exec ruby script.rb` uses Bundler to set the correct LOAD_PATH for gems in Gemfile.lock. Gems are only loaded when explicitly required in script.rb, ensuring the correct versions and their dependencies are used.