Gemfile for project dependencies in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Gemfile in a Ruby project?

A Gemfile is a file that lists all the Ruby gems (libraries) your project needs. It helps manage and install these dependencies easily.

beginner

How do you specify a gem and its version in a Gemfile?

You write: gem 'gem_name', '~> version_number'. For example, gem 'rails', '~> 7.0' means use Rails version 7.0 or compatible updates.

beginner

What command do you run to install gems listed in the Gemfile?

You run bundle install. This reads the Gemfile and installs all the listed gems.

beginner

What is the purpose of the source line in a Gemfile?

The source line tells Bundler where to find gems, usually https://rubygems.org, the main Ruby gem repository.

intermediate

How can you group gems for specific environments in a Gemfile?

You use group :environment_name do ... end. For example, group :development do gem 'pry' end means the gem is only for development.

What does the command bundle install do?

A Installs all gems listed in the Gemfile

B Creates a new Gemfile

C Removes unused gems

D Updates Ruby version

bundle install reads the Gemfile and installs all the gems your project needs.

How do you specify the source for gems in a Gemfile?

A install source 'https://rubygems.org'

B gem 'source', 'https://rubygems.org'

C use 'https://rubygems.org'

D source 'https://rubygems.org'

The source line at the top of the Gemfile tells Bundler where to find gems.

Which syntax correctly adds the gem 'rails' version 7.0 or higher but less than 8.0?

A gem 'rails', '~> 7.0'

B gem 'rails', '>= 7.0'

C gem 'rails', '= 7.0'

D gem 'rails', '< 7.0'

The ~> operator means compatible with version 7.0, but less than 8.0.

How do you add gems only for the development environment?

A gem 'pry', environment: 'development'

B group :development do gem 'pry' end

C if environment == 'development' gem 'pry' end

D gem 'pry' only: :development

Using group :development do ... end wraps gems for that environment.

What file does Bundler create to lock gem versions after installing?

A gems.locked

B Gemfile.txt

C Gemfile.lock

D bundle.lock

Bundler creates Gemfile.lock to record exact gem versions installed.

Explain the purpose of a Gemfile and how it helps manage project dependencies.

Think about how you tell your project what tools it needs.

Describe how to group gems for different environments in a Gemfile and why this is useful.

Consider when you want some tools only during development.