This post will demonstrate how to create your own Ruby Gem.

It will the first in a three-part series that covers the following:

It will work off the code written in "RSpec With GitHub Actions".

Source code can be found here.

We will clone the project rspec-github-actions and use Bundler to initialize the project:

$ git clone https://github.com/okeeffed/rspec-github-actions.git
$ cd rspec-github-actions
# Checkout the starting point
$ git checkout 1-rspec-with-github-actions

# Make the related gemspec
$ touch contrived_math.gemspec
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At this stage, our project is now ready to start working with.

Details about our Gem will be added into the contrived_math.gemspec file that was created.

I have filled out my details, and so it looks like so:

Gem::Specification.new do |s|
  s.name        = 'contrived_math'
  s.version     = '0.0.0'
  s.summary     = 'Hello, World!'
  s.description = 'A simple hello world gem'
  s.authors     = ["Dennis O'Keeffe"]
  s.email       = 'hello@dennisokeeffe.com'
  s.files       = ['lib/contrived_math.rb']
  s.homepage    =
    'https://rubygems.org/gems/contrived_math'
  s.license = 'MIT'
end
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At this point, we can build the gem locally.

We can build the gem with a simple gem build command.

In the terminal, run the following:

$ gem build contrived_math.gemspec
  Successfully built RubyGem
  Name: contrived_math
  Version: 0.0.0
  File: contrived_math-0.0.0.gem
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Once built, it will output the file into the current working directory.

We can install that by referencing it directly:

$ gem install ./contrived_math-0.0.0.gem
Successfully installed contrived_math-0.0.0
Parsing documentation for contrived_math-0.0.0
Installing ri documentation for contrived_math-0.0.0
Done installing documentation for contrived_math after 0 seconds
1 gem installed
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At this point, we can test it our in an interactive environment.

Open up IRB and do just that:

$ irb
irb(main):001:0> require 'contrived_math'
\=> true
irb(main):002:0> ContrivedMath.add(1, 2)
=> 3
irb(main):003:0> ContrivedMath.subtract(1, 2)
=> -1
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Success!

Today's post demonstrated how to create our first Ruby gem.

In the next post, we will demonstrate how to deploy it to the gem package repository.

Photo credit: joshwithers