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Testing frameworks for Ruby
Introduction
A testing framework is used is used on a software project when it has grown large enough that manual debugging and system upkeep would be too time and resource intensive. The framework provides a way to automate testing to provide for low cost maintenance. The framework itself contains a set of assumptions, concepts, and tools that allow for various types of testing. Choosing the right framework depends on many factors associated with the system in development and the mindset of the developers and stakeholders. Every framework has a few basic features: A process for defining the format to express user expectations, a way to execute the tests, and a way to report the results of the test to the user.
Definition
Test Driven Development (TDD)
Test driven development is the process of writing tests first and foremost. These tests represent desired improvements and or new functionality in the system, and since they haven’t been implemented yet they must fail when initially run. Then code is written until these tests can be passed, assuring that the desired behavior is exhibited by the code. Then the code is rewritten to acceptable standards.
Behavior Driven Development(BDD)
Behavior driven development is very similar to test driven development. It is a different approach to the same subject. With this type of development users are more focused on the behavior that is exhibited in the code and less on testing each method and class. The goal of BDD is to use terminology focused on the behavioral aspects of the system to allow a seamless transition between specification, design, and implementation of a system. BDD has a much better alignment with business concerns.
Mocking in Testing
Mocking provides users with a helpful way to write unit tests for objects that will act as a mediator to it. Mock objects are used to imitate existing roles in a system. Instead of calling these real objects, the mock objects are called instead. They will assert that the correct methods were called with the right parameters and in the right order. So instead of needing to create a database and fill it with rows, we can instead use a mock object that would supply the same information as the database. It is the high coupling between modules and tests that creates the need for a mocking framework.
Benchmarking in Testing
Benchmark is used to determine things like throughput performance and CPU and memory performance. It is good practice to perform benchmark testing on any system going into a production environment. This allows you to determine current performance in order to improve upon it by refining code or database configurations. Benchmark tests must be run inside a repeatable environment in order to yield results that can be accurately compared.
Testing Framework
A testing framework allows for automated software testing. It contains a set of assumptions, concepts, and tools that assist in this testing. The main advantage of using a testing framework is the lower cost for maintenance. The testing framework is responsible for :
- defining the format in which to express expectations
- creating a mechanism to hook into or drive the application under test
- executing the tests
- reporting results
Testing Framework Evolution
Test driven development is linked with the concepts of extreme programming which began in 1999. It offers more than just simple validation of correctness; it can also drive the design of a program. By focusing on the test cases first, one must imagine how the functionality will be used by clients. Test-driven development ensures that all written code is covered by at least one test. This gives the programming team, as well as users and stakeholders, a greater level of confidence in the code.
One major problem with TDD is that its mindset takes us in a different direction. Users needed to start thinking in terms of behavior specifications, not verification tests. This required two things:
- A language shift in traditional TDD
- Driving your tests from a domain/user story perspective rather than technical perspective
TDD vs BDD
Give high level example how they differ from each other.
Ruby Testing Frameworks
Compared to five years ago the number of testing framework available for ruby has increased rapidly. Selecting a perfect testing framework for a particular project has become harder.
Overview of testing framework
Selection of testing framework for ruby projects depends on factors like what are we trying to accomplish TDD or BDD, is GUI testing included, is acceptance testing required, do we have to merge legacy ruby test code with new testing framework. Altough GUI testing and acceptance testing are out of scope for this wiki we have made attempt to cover them in some details at the end of this wiki page. Meanwhile, below is the detailed explanation of four most commonly used unit testing framework.
Test:Unit
Test-Unit is one of the oldest testing frameworks for ruby testing. Test-Unit is basically used for performing test driven development same as how Java’s JUnit is used. It’s in a way very similar to java’s JUnit. Test-Unit framework when initially released was part of the ruby distribution package. The newer version since then has been converted to gems and has been provided to developers as a standalone package. Additionally some of the features like notify, capybara, GTK+, Tk, and FOX Toolkit have been split from package and provided as a separate packages.
RSpec
RSpec is a Behavior-Driven Development tool for Ruby programmers. As defined earlier BDD is an approach to software development that combines Test-Driven Development, Domain Driven Design, and Acceptance Test-Driven Planning. RSpec helps you do the TDD part of that equation, focusing on the documentation and design aspects of TDD [1]
RSpec is one of the most widely used testing frameworks for ruby. The main difference between RSpec and Test-Unit is semantics. RSpec provides a way to write tests which are more in human readable form. This reduces the expense for maintaining the test and also provides more easily understandable tests. Additionally when RSpec tests fails it provides more information about what functionality failed and why compared to Test-Unit test where you have to put custom messages on all assertion statements to point out exactly what happened.
Riot
Riot is another BDD ruby unit testing framework. Riot testing framework is a mixture of both RSpec and Test-Unit or should say RSpec and Shoulda (which is based on Test-Unit). The main purpose of the author of Riot testing framework was to come up with some ruby testing framework which is fast in execution but is in more human readable form. As in case of other testing framework Riot does not have variables described or initialized in its test cases. It has a setup block which returns a variable as default. This allows Riot to be fast during execution as it does not have to initialize or do much of pre-test setup. One of the uniqueness about Riot testing framework is that the tests only focuses on small functionality.
Shoulda
Due to the fact that Test-Unit was the first testing framework available for ruby there are many legacy ruby projects out there where they have implemented test suites using Test-Unit. For such projects adopting to a new testing framework while maintaining the old test suites becomes nightmare. For the very same reason Shoulda test framework was developed. Shoulda testing framework is derived from Test-Unit. Shoulda testing framework is a BDD based testing framework that easily integrates with old legacy Test-Unit test suites. TDD can also be easily achieved by using Shoulda testing framework.
Testing Framework Details
| Testing Framework | Released Date | Released Version | Current Version | Testing Type Supported | Install Command | Documentation/Version Support |
|---|---|---|---|---|---|---|
| Test:Unit | 03-20-2008 | 1.2.3 | 2.4.0 | TDD,Mocking | gem install test-unit | Test:Unit Site |
| Shoulda | 04-26-2008 | 4.1 | 2.11.3 | BDD,TDD | gem install shoulda | Shoulda Site |
| RSpec | 05-26-2008 | 1.1.4 | 2.6.0 | BDD,TDD, DDD (Domain Driven Design) | gem install rspec | RSpec Site |
| Riot | 10-19-2009 | 0.9.11 | 0.12.5 | BDD,TDD | gem install riot | Riot Site |
| Cucumber | 05-20-2009 | 0.3.6 | 1.0.6 | Acceptance Testing | gem install cucumber | Cucumber Site |
The above table displays information about most of the popular testing frame. It includes when this testing frameworks were released and what was the released version. It also displays their current version available. The list also includes some of the new testing frameworks like Riot.
Examples
Above we described how each ruby testing framework differ from each other. But to better understand each testing framework let go through a single example with tests written in most testing framework described above.
TravelTime
The example that we have used below is a simple travel time example. All it does is if you give it a distance between two cities it will calculate the time it will take you to travel from City A to City B. It assumes that you will be driving at 60 miles/Hr with minimal traffic on the road.
class TravelTime
attr_accessor :distance
#Divide the distance by 60 and return the float
def time_to_travel
@time = @distance.fdiv(60)
end
#Format the float to two decimal and return the string
def format_time_to_travel(time)
@time = format("%3.2f",time)
end
def initialize(distance)
@distance = distance
end
end
The code above has two functions and one initialize function. The initialize function takes in distance between two cities and stores it into distance variable. The first function time_to_travel when called calculates the time it takes to travel by dividing the distance provided during initialize stage by 60 (for 60 miles/hr speed). This function returns a float value as time. The second function format_time_to_travel all it does is if you provide a float number it will format the float number up to two decimal points and return the string. This function will be used in cases where you get a big float number for time like 2.36666667 hrs and you just want it to be 2.37 than you can pass the float number to get 2.37 hrs. Now lets see how this functions can be tested in different testing framework.
Test-Unit
The first test framework that we are going to use is Test-Unit. The code for TravelTimeTest_TU class is shown below which seems similar to Java JUnit test code. The class below has setup function which is used for setting up pretest data before running tests. In our case we have initialized three different instances of TravelTime class with distances 120 150 and 135 miles. The class also has a teardown function which can be used to discard all the data that were created before or during test execution. The remaining three functions are the actual tests that will be ran once this test is executed.
gem 'test-unit'
require 'test/unit'
require File.dirname(__FILE__) + '/travel_time'
class TimeTravelTest_TU < Test::Unit::TestCase
# Called before every test method runs. Can be used
# to set up fixture information.
def setup
@traveltime1 = TravelTime.new(120)
@traveltime2 = TravelTime.new(150)
@traveltime3 = TravelTime.new(135)
end
def teardown
# Do nothing
end
def test_time_to_travel_integer
time = @traveltime1.time_to_travel
assert_equal 2.0, time
end
def test_time_to_travel_floatWithOneDecimal
time = @traveltime2.time_to_travel
assert_equal 2.5, time
end
def test_time_to_travel_floatWithTwoDecimal
temp = @traveltime3.time_to_travel
time = @traveltime3.format_time_to_travel(temp)
assert_equal "2.25", time
end
end
The first test function is to test if you provide the distance of 120 miles does it return the travel time to be 2 hrs. The second test function tests if you provide 150 miles distance does it come back with 2.5 hrs. And the last test function checks if you get travel time in a big floating number like 2.2444445 hours can you correctly format that result to 2.25 hours. We have used different instances of travel time class for different tests the reason for doing this is to see if the performance suffers between test frameworks. The results for this test are shown below. It shows that three test as described above were ran and 3 assertions were executed. All the tests passed. Executing this test took 0.004 seconds which is fast compared to some of the other test frameworks described below.
Finished in 0.004 seconds. 3 tests, 3 assertions, 0 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications 100% passed
RSpec
The second testing framework that we implemented was RSpec. As described in section 3.1 above RSpec test framework is a BDD test framework which gives you more information about your test when it fails. As you can see below it does not have setup or teardown functions as Test-Unit for pretest data setup or discarding data. All the test scenarios for RSpec framework are included inside a describe block. The individual tests are included inside an it block.
gem 'rspec'
require File.dirname(__FILE__) + '/travel_time'
#spec TravelTimeTest_RSpec.rb --format specdoc #Command to run from command line
describe TravelTime do
it "should be 2.0 hours when distance is 120 miles" do
@traveltime1 = TravelTime.new(120)
time = @traveltime1.time_to_travel
time.should be == 2.0
end
it "should be 2.5 hours when distance is 150 miles" do
@traveltime1 = TravelTime.new(150)
time = @traveltime1.time_to_travel
time.should be == 2.5
end
it "should be 2.25 hours when distance is 135 miles" do
@traveltime1 = TravelTime.new(135)
temp = @traveltime1.time_to_travel
time = @traveltime1.format_time_to_travel(temp)
time.should be == "2.25"
end
end
As seen from above we have three it blocks which include our three test scenario's. All the it blocks have a string statement which describes the test case. In case a test fails it will display this string to show what functionality is broke. So for example if last test case fails it will show that TravelTime should be 2.25 hours when distance is 135 miles but the return value was 2.45. This is the reason RSpec is more popular over Test-unit as it describes what went wrong and where. The result produced after executing this test is shown below. It shows all the test case passed and it also shows what test cases were run. One of the downside of using RSpec framework is that it takes more time to execute than Test-Unit which can be seen below as it takes more time than Test-Unit.
TravelTime - should be 2.0 hours when distance is 120 miles - should be 2.5 hours when distance is 150 miles - should be 2.25 hours when distance is 135 miles Finished in 0.249016 seconds 3 examples, 0 failures
Riot
The third testing framework that we test was Riot. Riot is pretty new testing framework and not very popular as of today. But we ended up selecting Riot as it has some interesting qualities. Riot testing framework gives you flavor of both worlds RSpec and Test-Unit. Riot test framework is not based on test-unit but gives you some of the functionality for test-unit and the BDD functionality of RSpec while reducing the execution time. As seen from below Riot test are usually define between a context block. This block can contain one or more setup and asserts blocks. In our test we have created three context blocks to test each case individually.
gem 'riot'
require 'riot'
require File.dirname(__FILE__) + '/travel_time'
context TravelTime do
setup {TravelTime.new(120)}
asserts("Travel time is 2.0 hours when distance is 120 miles"){
topic.time_to_travel == 2.0
}
end
context TravelTime do
setup {TravelTime.new(150)}
asserts("Travel time is 2.5 hours when distance is 150 miles"){
topic.time_to_travel == 2.5
}
end
context TravelTime do
setup {TravelTime.new(135)}
asserts("Travel time is 2.25 hours when distance is 135 miles"){
topic.format_time_to_travel(topic.time_to_travel) == "2.25"
}
end
As seen from above the three context blocks test the same three cases but it has some new setup blocks. The setup block in each case does not instantiate any variables like Test-Unit. The entire setup box returns common single item topic. This topic is used in asserts blocks to see if the condition is met. This enables riot to execute faster as it does not have to go generate variables like other testing frameworks. All the assert block has strings like RSpec for notification. From the results below you can see that Riot testing frameworks is executed in the same time as Test-Unit but it also shows the tests that were executed like RSpec. Riot was by far the easiest of all the testing framework to write.
TravelTime + asserts Travel time is 2.0 hours when distance is 120 miles TravelTime + asserts Travel time is 2.5 hours when distance is 150 miles TravelTime + asserts Travel time is 2.25 hours when distance is 135 miles 3 passes, 0 failures, 0 errors in 0.004 seconds
Shoulda
The last testing framework that we tested was Shoulda. Shoulda is kind of similar to Riot but is directly derived from Test-Unit. We included this framework as it’s one of the popular frameworks used out in real world. Shoulda is also a mix of RSpec and Test-Unit. It’s a BDD testing framework. Similar to Test-Unit it has a setup block which is used to instantiate variable. It uses the should block like RSpec to describe test scenarios.
gem 'shoulda'
gem 'shoulda-context'
gem 'test-unit'
require 'test/unit'
require File.dirname(__FILE__) + '/travel_time'
class TravelTimeTest_Shoulda < Test::Unit::TestCase
context TravelTime do
setup do
@traveltime1 = TravelTime.new(120)
@traveltime2 = TravelTime.new(150)
@traveltime3 = TravelTime.new(135)
end
should "be 2.0 hours when distance is 120 miles" do
time = @traveltime1.time_to_travel
assert_equal 2.0,time
end
should "be 2.5 hours when distance is 150 miles" do
time = @traveltime2.time_to_travel
assert_equal 2.5,time
end
should "be 2.25 hours when distance is 135 miles" do
temp = @traveltime3.time_to_travel
time = @traveltime3.format_time_to_travel
assert_equal "2.25",time
end
end
end
As seen from the code above it has same three test cases and has three assert statements. As RSpec it also has string messages for display. The result generated from this test is shown below and as you can see the timing is quite similar to Test-Unit and Riot.
Started ...F... Finished in 0.004500 seconds. 3 tests, 3 assertions, 0 failures, 0 errors, 0 skips
Additional Testing Framework
UI Testing Framework
Context
Win32-AutoGUI
Acceptance testing
In addition to the unit testing frameworks discussed above there are testing frameworks that work as acceptance testing framework for ruby projects. They do the same functionality as unit testing but are more like documentation and business criteria driven testing. Some of this type of testing framework includes cucumber which is described below.
Cucumber
Cucumber is designed to allow you to execute feature documentation written in plain text (often known as "stories") [2]. Cucumber testing framework is a basic testing framework which allows you to describe your test cases in plain English text. On the back end you make a file with regular expression which can parse this plain English text and perform the test case. Today cucumber is widely used in ruby projects especially with RSpec testing framework.
References
- [1] RSpec Info RSpec Info Site
- [2] Mike Gunderloy Cucumber: The Latest in Ruby Testing