+++
date = "2011-02-11"
title = "Narf: A Ruby Micro Test Framework"
tags = ["Ruby", "Test", "testing", "bdd", "tdd", "agile"]
slug = "narf-a-ruby-micro-test-framework"
+++
I'm a happy user of RSpec, Cucumber and sometimes Steak. Great tools to
write specs and features and prove my application does what it's
supposed to do. But sometimes I have the need for something more _light
weight_.
~
For example, sometimes I need to write a single ruby method. Just something
'quick' to import a file, convert some data or whatever. Being a good
citizen I want to test that method.

Using RSpec or Cucumber here just seems wrong here. So, I've implemented
my own _Ruby Micro Test Framework_: *Narf*

``` ruby
def assert(message, &block)
  puts "#{"%6s" % ((yield || false) ? '  PASS' : '! FAIL')} - #{message}"
end
```

(Yes, that's it.)

With this simple method, added to your ruby file, you can test your
method. And example:

Let's say you're going to write a method that counts how often the word
'ruby' occurs in a given String:

``` ruby
def count_rubies(text)
  # TODO
end

#--- Ruby Micro Test Framework
def assert(message, &block)
  puts "#{"%6s" % ((yield || false) ? '  PASS' : '! FAIL')} - #{message}"
end
#---

#--- Tests
assert "Count zero rubies" do
  count_rubies("this is Sparta!") == 0
end

assert "Count one ruby" do
  count_rubies("This is one ruby") == 1
end

assert "Count one RuBy" do
  count_rubies("This is one RuBy") == 1
end
```

Now, simple save this file and feed it to ruby:

``` shell
$ ruby my_method.rb
! FAIL - Count zero rubies
! FAIL - Count one ruby
! FAIL - Count one RuBy
```

Now, implement your method...

``` ruby
def count_rubies(text)
  text.match(/(ruby)/i).size
end
```

And re-run your tests:

``` shell
$ ruby my_method.rb
  PASS - Count zero rubies
  PASS - Count one ruby
  PASS - Count one RuBy
```

So with the addition of just a single method you can fully TDD/BDD your
single method Ruby code. Pretty need, huh?

[Need codez?][1]

 [1]: http://github.com/ariejan/narf