Ruby - How to Unit Test your Codes

This post demonstrates how to unit test your Ruby codes. Note that Ruby-on-Rails (RoR) is not used here.

Installation Details

Windows 10
Ruby 2.3.1
- ruby 2.3.1p112 (2016-04-26 revision 54768) [x64-mingw32]

The Ruby Application

The ruby application is a simple Calculator program that can add, subtract, multiple, and divide integral numbers.

Directory Structure

We have a simple directory structure for our application. Under the src folder, we have rb and tests folders.

rb – contains our Calculator codes
tests – contains our unit tests

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Calculator Code

This file is named as SimpleCalculatorClass.rb.

class SimpleCalculatorClass 

    def add(a, b)
        return a + b
    end

    def sub(a, b)
        return a - b
    end

    def mul(a, b)
        return a * b
    end

    def div(a, b)
        return a / b
    end
end

class SimpleCalculatorClass

def add(a, b)

return a + b

end

def sub(a, b)

return a - b

end

def mul(a, b)

return a * b

end

def div(a, b)

return a / b

end

Unit Test Codes

This file is named SimpleCalculatorClassTests.rb.

require 'test/unit'
require_relative '../rb/SimpleCalculatorClass'

class SimpleCalculatorClassTests < Test::Unit::TestCase
    
    Test::Unit.at_start do
      puts 'START: runs only once at start'
    end

    Test::Unit.at_exit do
      puts 'END: runs only once at end'
    end

    def setup
        puts "Runs before each test method"
        @cal = SimpleCalculatorClass.new()
    end

    def teardown
        puts "Runs after each test method"
    end    

    def test_add()

        assert_equal(2, @cal.add(1,1))
    end

    def test_sub()
        assert_equal(0, @cal.sub(1,1))
    end

    def test_mul()
        assert_equal(12, @cal.mul(4,3))
    end

    def test_div()
        assert_equal(1, @cal.div(4,3))
    end
end

require 'test/unit'

require_relative '../rb/SimpleCalculatorClass'

class SimpleCalculatorClassTests < Test::Unit::TestCase

Test::Unit.at_start do

puts 'START: runs only once at start'

end

Test::Unit.at_exit do

puts 'END: runs only once at end'

end

def setup

puts "Runs before each test method"

@cal = SimpleCalculatorClass.new()

end

def teardown

puts "Runs after each test method"

end

def test_add()

assert_equal(2, @cal.add(1,1))

end

def test_sub()

assert_equal(0, @cal.sub(1,1))

end

def test_mul()

assert_equal(12, @cal.mul(4,3))

end

def test_div()

assert_equal(1, @cal.div(4,3))

end

There are several things to take notice of.

require ‘test/unit’

We import the test/unit module. This is something similar to importing Junit in Java.

require_relative ‘../rb/SimpleCalculatorClass’

We include our SimpleCalculator.rb script into this unit test so that we can use the SimpleCalculatorClass class.

Test::Unit::TestCase

Unit test classes extend from Test::Unit::TestCase

Test::Unit.at_start

This runs once before any test method is executed.

Test::Unit.at_exit do

This runs once after all test methods are executed.

setup method

This runs right before each test method is executed.

teardown method

This runs right after each test method is executed.

test_* methods

These are your test methods

Sample Test Output

Download the codes

https://github.com/Turreta/Ruby-How-to-Unit-Test-your-Codes

Installation Details

The Ruby Application

Directory Structure

Calculator Code

Unit Test Codes

require ‘test/unit’

require_relative ‘../rb/SimpleCalculatorClass’

Test::Unit::TestCase

Test::Unit.at_start

Test::Unit.at_exit do

setup method

teardown method

test_* methods

Sample Test Output

Download the codes

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