CSC/ECE 517 Fall 2011/ch2 2e gp

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

major components 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

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 login_system.feature
 
     Feature: User Login
 
     As a User 
     I want to Login to the system 
     So that I can Post a New Employee

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

     Scenario : Login Successful

     Given a user whose is verified
     When I type in the username and password
     Then the user Logs in

When a scenario is ready following command is issued

     $script/cucumber features/login_system.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

     eim/features/step_definitions$  nano login_steps.rb

           Given /^user is verified$/ do
             pending
           end
           Then /^the user "(.+)" can log in with password "(.+)"$/ do |username, password| 
             visit login_path 
             fill_in "login", :with => username 
             fill_in "password", :with => password 
             click_button "Log In" 
             response.should contain("Logged in Successfully") 
           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.

References

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