Testing Frameworks for Ruby

This page serves as a knowledge source for understanding the different Testing Frameworks available for Ruby.

Introduction

No code is perfect from the word go! Testing plays an important role in System Development Life Cycle. During testing, we follow a taxonomic procedure to uncover defects at various stages. A test framework provides various Test Types, Test Phases, Test Models, Test Metrics and acts as a guideline as to how to perform effective testing <ref> http://www.scribd.com/doc/15909730/Software-Testing-Framework </ref>. Various testing tools are available for Rubylanguage, each having some unique features over others. Here is a brief introduction and feature comparisons of popular testing frameworks.

Testing Approaches

Before we delve into testing for Ruby, in general, these are the followed approaches in industry today

Test Driven Development

This strategy, (abbreviated as TDD) <ref> http://en.wikipedia.org/wiki/Test-driven_development </ref>, though cumbersome due to its methodology develops efficient code. First a unit test is written for a function, even before the code for that function is developed. Based on this test minimal code is developed to ensure the test succeeds; if not the code is modified until test run successfully. In this iterative approach, effort is made to ensure flawless code is developed.

Behavior Driven Development

BDD <ref> http://en.wikipedia.org/wiki/Behavior_Driven_Development </ref> as its popularly know, upholds the traditional iterative workflow of Test Driven Development, but it focuses on defining behaviors that is easy to understand to naive people (with no programming background) by writing tests in natural language. This approach focuses more on looking at code development from a behavioral abstraction. For example testing the code for a recipe belonging to a category of a cookbook, in BDD would be something like 'A recipe can't be without a category'

Unit Testing

Unit Testing is a method by which we can isolate and test a unit functionality of the program, typically individual methods during and long after the code is written.

Cucumber

Cucumber is a testing tool that follows the BDD approach of testing. Cucumber written itself in Ruby programming language allows the execution of feature documentation written in natural language often termed as [user stories]

Features of Cucumber

Terminology of Cucumber

Stakeholder - A person who gets some value out of the system like an administrator
Feature - A feature is a piece of system functionality that delivers value to one or more stakeholders
User story - It is a rough description of scope for future work used as planning tools. Most common format for the stories are - "in order to...","as a...","I want"
Feature file - It describes a feature or a part of feature with illustrative example of expected results
Key Example - Each feature is illustrated with Key Examples which show what are expected in a given test case
Scenario - Scenario captures one key example for a feature file. It represents how stakeholder gets some value from that system. Example of good scenarios for checking login module includes user not signed up, password has expired
Step - Steps are domain language phrases which can be combined to write scenarios. They combine a GWT directive with a regular expression to evaluate something and add a simple ruby code which tells the step what should be done further

Pattern

Cucumber follows a GWT (Given-When-Then) pattern for developing test cases. In the scenarios written for Cucumber, we state what a given scenario is, when we are presented with information and then what should happen so that the logic of information can be validated.

Example

Cucumber is a high-level testing tool that defines the feature specs. An typical [example] for a Cucumber Scenario is shown below - First we need to install the Cucumber gem on Ruby using this simple command

     $gem install cucumber-rails
         Successfully installed cucumber-rails-0.3.0
         1 gem installed
         Installing ri documentation for cucumber-rails-0.3.0...
         Installing RDoc documentation for cucumber-rails-0.3.0...

When installed, a basic Cucumber test is generated using generator script

     $script/generate rspec
     $script/generate cucumber
           force  config/database.yml 
           create  config/cucumber.yml 
           create  config/environments/cucumber.rb 
           create  script/cucumber 
           create  features/step_definitions 
           create  features/step_definitions/web_steps.rb 
           create  features/support 
           create  features/support/paths.rb 
           create  features/support/env.rb 
           exists  lib/tasks 
           create  lib/tasks/cucumber.rake

A feature file is next created with name feature_name.featrue . the Feature is described in the Feature: directive, followed by the story. The story is written in the format shown in the code: As a <role> , I want <feature> , So that <business Value>.

     $ nano tasklist.feature
 
     Feature: Tasks

     In order to keep track of tasks
     People should be able to
     Create a list of tasks

Each feature can have multiple scenario. One such scenario for the login feature is as shown below

     Scenario: List Tasks
     Given that I have created a task "task 1"
     When I go to the tasks page
     Then I should see "task 1"

When a scenario is ready following command is issued

     $script/cucumber features/tasklist.feature
           0 scenarios
           0 steps

Steps can be added to scenarios, which are combination of a GWT directive, a regular expression and a block of ruby code which states what this step does

     /features/step_definitions$nano tasklist_steps.rb

           Given /^that I have created a task "(.*)"$/ do |desc|
             Task.create!(:description => desc)
           end
           When /^I go to the tasks page$/ do
             visit "/tasks"
           end

Test::Unit

The in-built, ready to use unit testing mechanism for Ruby is called Test::Unit.It belongs to the XUnit family unit testing framework. It has a setup method for initialization, a teardown method for cleanup and the actual test methods itself. The tests are bundled separately in a test class in the code it is aimed to test.

Features

This salient features of the Test::Unit Framework are:-

Assertions

We can use Test::Unit to make assertions. The test is successful if the assertion is true and fails if the assertion is false. All the assertion methods provided by test::unit can be found at Test::Unit::Assertions.

assert( boolean, [message] )	True if boolean
assert_equal( expected, actual, [message] ) assert_not_equal( expected, actual, [message] )	True if expected == actual
assert_raise( Exception,... ) {block} assert_nothing_raised( Exception,...) {block}	True if the block raises (or doesn't) one of the listed exceptions.

Test-Fixtures

Using a test fixture, we can initialize (and cleanup) the common set of data for two or more tests hence eliminating unnecessary duplication. Fixtures are written in the setup() and teardown() methods.

Test-Suite

As unit tests increase in number for a given project, it becomes tough running them one at a time. It is hence useful to combine a bunch of related test cases and run them as batch. Test::Unit provides a class called TestSuite for this purpose<ref>[1]</ref>.

Example Test

The Test::Unit::TestCase class is the main class and the BinarySearchTest is the subclass, it overrides setup and teardown methods. All test methods start with 'test_' prefix thus differentiating helper methods from main methods. The Test::Unit::TestCase class makes the test methods into tests, wrapping them into a suite and running the individual tests. The results are collected into Test::Unit::TestResult object.

   require 'test/unit'
   require 'binarysearch'

   class BinarySearchTest < Test::Unit::TestCase

     def setup
       @input_array = [1,2,3,4,5]      #The test fixture is initialized        
     end
     
     def test_success_left_half
       assert_equal(binary_search(@input_array,1),true)   #tests if the element present in left half of the array is found
       assert_equal(binary_search(@input_array,2),true)    
     end

     def test_success_right_half
       assert_equal(binary_search(@input_array,5),true)   #tests if the element present in the right half of the array is found
       assert_equal(binary_search(@input_array,4),true)
     end

The tests are run by running the file binary_search_test.rb.Sample results for the above test is shown below.

 Loaded suite binarysearch
 Started
 F...
 Finished in 0.32 seconds.
 
   1) Failure:
 test_failure(BinarySearchTest) [binarysearch.rb:22]:
 <true> expected but was
 <false>.
 
 4 tests, 6 assertions, 1 failures, 0 errors

Shoulda

Shoulda makes it easy to write refined, intelligible, and maintainable tests. Shoulda consists of matchers, test helpers, and assertions. It’s fully compatible with your existing tests in Test::Unit or RSpec, and requires no retooling to use.

Matchers Test::Unit- and RSpec-compatible one-liners that test common Rails functionality. These tests would otherwise be much longer, more complex, and error-prone.

Helpers

context and #should give you RSpec like test blocks in Test::Unit. In addition, you get nested contexts and a much more readable syntax.

Assertions Many common Rails testing idioms have been distilled into a set of useful assertions.

CSC/ECE 517 Fall 2011/ch2 2e gp