Unit Testing with Minitest
Memphis Ruby Users Group
Josh W Lewis - @joshwlewis
Plia Systems
In computer programming, unit testing is a method by which individual units of source code, sets of one or more computer program modules together with associated control data, usage procedures, and operating procedures are tested to determine if they are fit for use.- Wikipedia
TL;DR
Unit testing is code that makes sure your code works.
Why Unit Test?
- Confidence
- Speed
- Refactorability
- Quality
- Reliability
- Documentation
Minitest is Awesome!
github.com/seattlerb/minitest
- Lightweight
- Ships with Ruby
- Unit or Spec style tests
- Mocking and Stubbing
- Benchmarking
Test/Unit style tests are standard with Minitest
class User < ActiveRecord::Base
def initials
(first_name[0] + middle_name[0] + last_name[0]).upcase
end
end
class TestUser < Minitest::Test
def setup
@user = User.new first_name: 'Josh', middle_name: 'Wayne',
last_name: 'Lewis'
end
def test_initials
assert_equal @user.initials, 'JWL'
end
end
Spec style tests are also available with Minitest
class User < ActiveRecord::Base
def initials
(first_name[0] + middle_name[0] + last_name[0]).upcase
end
end
describe User do
subject { User.new first_name: 'Josh', middle_name: 'Wayne',
last_name: 'Lewis' }
describe :initials do
it 'should return first letter of all names' do
subject.initials.must_equal 'JWL'
end
end
end
Let's make an app for that...
My boss wants something to translate English to Pig Latin and Pig Latin to English. And he wants it to remember previous translations.
rails new pig_latin --database=postgresql --skip-test-unit
Source available at: github.com/joshwlewis/pig_latin
Use minitest-rails to bootstrap your test suite
Gemfile
gem 'minitest-rails', '~> 0.9.0', group: [:development, :test]
bundle install
rails generate mini_test:install
test/test_helper.rb
ENV["RAILS_ENV"] = "test"
require File.expand_path('../../config/environment', __FILE__)
require "rails/test_help"
require "minitest/rails"
# ...
bundle exec rake test
Automated testing enables TDD workflow
Gemfile
gem 'guard-minitest'
Guardfile
guard :minitest do
watch(%r{^test/(.*)_test\.rb})
watch(%r{^lib/(.+)\.rb}) {|m| "test/#{m[1]}_test.rb"}
watch(%r{^test/test_helper\.rb}) {'test'}
watch(%r{^app/(.+)\.rb}) {|m| "test/#{m[1]}_test.rb"}
# ...
end
The Payoff...
-
Code Test Coverage:
-
Continuous Integration:
- Continuous Deployment: pig-latin.herokuapp.com
Resources
- Minitest documentation
- Minitest Quick Reference
- Rails Assertions
- Pig Latin Translator
- This Presentation