Testing

Rails testing has serveral options: MiniTest, RSpec, Test::Unit, Cucumber. Test Frameworks make it easier to write and maintain tests. Rake provides rake test and other variations for automated testing.

Example Gemfile for test environment:

group :test do
  gem 'minitest-reporters', '1.0.5'
  gem 'mini_backtrace',     '0.1.3'
  gem 'guard-minitest',     '2.3.1'
end

MiniTest

Testing Framework in Ruby's vast Standard Library. Faster than RSpec by running tests in parallel. Written more like Ruby code.

Used for unit testing in rails. ActiveRecord::TestCase inherits MiniTest::Test. Automatically generated in Rails for each model.

class TruthTest < MiniTest::Unit::TestCase
  def test_truth
    assert true
  end
end

Checks truth by each assert statement.
In MiniTest this is done with assertions that will test the object by assert something about it. Take this example of a Post model test.

post = Post.create(title: 'Post title')
# post should be valid
assert post.valid?

Here we are creating a post object and checking if it is valid to ensure that it got created.

RSpec

One of the built-in ruby testing frameworks. Run test cases in Rails with bin/rspec (reqiures being initialized).

• Popular, but requires learning a full DSL and is slower than MiniTest counterpart
• Less code need because of DSL (and more readable)

• Good for running individual tests

  require 'rspec'
  describe "Truth" do
  it "should be true" do
    true.should == true
  end
  end

Rails Fixture Testing

Built-in to ActiveRecord, Fixtures let you test the ActiveRecords themselves (testing on the database) by populating the testing database with sample data (in yaml format).

• I always test my validations as these are important to the health of your application, you don't want an accidental deletion or typo to ruin your application.
• If you get an error in your application, before fixing it in the code, first write a test (that will fail) and then when you fix it, the test will pass.
• Test any callbacks such as before_create to ensure that your data is being generated as you expected.
• Test any third party Gems that your models rely on. You never know when a new version of a Gem will do things differently or break your application.

Testing Controller and Views (Functional Testing)

Uses ActionController::TestCase < ActiveSupport::TestCase < MiniTest::Test. Also MiniTest! Introduces more asserts like assert_response for http responses.

Can be used to directly test http requests using the http VERBS:

test "should create article" do
  assert_difference('Article.count') do
    post :create, article: {title: 'Some title'}
  end
 
  assert_redirected_to article_path(assigns(:article))
end

Views can be tested using assert_select to verify HTML content on page:

assert_select 'title', "Welcome to Rails Testing Guide"

assert_select(selector, [equality], [message]) ensures that the equality condition is met on the selected elements through the selector. The selector may be a CSS selector expression (String) or an expression with substitution values.

assert_select(element, selector, [equality], [message]) ensures that the equality condition is met on all the selected elements through the selector starting from the element (instance of Nokogiri::XML::Node or Nokogiri::XML::NodeSet) and its descendants.

Integration Testing

Tests interaction among controllers. Test work flow for the application. In test/integration folder.

From ActionDispatch::IntegrationTest < ActiveSupport::TestCase.

• source: Comparing MiniTest to other frameworks
• source: Rails testing guide