Why use Minitest instead of RSpec?

Although RSpec is really popular, there are a few advantages of using Minitest:

1. Minitest is a standard library of Ruby since 1.9.3.
2. Minitest is fast and light-weight compared to RSpec.
3. Minitest provides both assertion-style and spec-style for writing test.

Minitest-ify your gem!

To add Minitest, we need to do the following:

1. Create a new folder test

The structure of the gem should be:

mygem
  + lib
  + test
    + spec
      - foo_spec.rb
    - test_helper.rb
  - mygem.gemspec
  - Rakefile

2. Add dependency to gemspec

# mygem.gemspec
# ...
Gem::Specification.new do |spec|
  # ...
  spec.add_development_dependency "minitest", ">= 5.8"
  spec.add_development_dependency "minitest-reporters", ">= 1.1"
end

3. Add a rake task to Rakefile

# Rakefile
# ...
require "rake/testtask"

Rake::TestTask.new do |t|
  t.libs << "test"
  t.test_files = FileList["test/**/*_spec.rb"]
  t.verbose = true
end

task :default => :test

4. Edit test_helper.rb

# test_helper.rb
require "minitest/autorun"
require "minitest/spec"
require "minitest/reporters"
require "mygem"

Minitest::Reporters.use!

5. Edit spec

# foo_spec.rb
require "test_helper"
describe Mygem do
  it "does something" do
    # ...
  end
end

6. Run test

> rake test

That’s it!