From: Alex Gutteridge <alexg@...>
Date: 2007-11-15T12:25:59+09:00
Subject: Re: test/unit question.   Accessing class variables?

On 15 Nov 2007, at 07:15, weathercoach@gmail.com wrote:

>   Hello.
>   This is my first attempt in trying to use the ruby library test/
> unit.   Additionally my programming and ruby skills are still around
> the beginner stage.
>
>  I have a unix utility which I've written in ruby and now that it
> actually does some work I want to be able to test it.    My first
> attempt at a unit test was to check the value of a class variable but
> this results in the following error
>
> NameError: uninitialized class variable @@bad_users in FindUsersTest
>
>   Here is a class and test which demonstrates what I'm trying to
> do.
>
> -- start class
> class Simple
> @@whatisit = "false"
>
>  def parse(n)
>    @@whatisit = true if n =~ /yes/
>  end
> end
>
> --- start test
> require 'simple'
> require 'test/unit'
>
> class SimpleTest <  Test::Unit::TestCase
>
>  def test_parse
>   v = Simple.new
>   v.parse("yes")
>
>  assert @@whatisit
>   end
> end
>
> --- run test
> ./test_simple.rb
> Started
> E
> Finished in 0.003813 seconds.
>
>  1) Error:
> test_parse(SimpleTest):
> NameError: uninitialized class variable @@whatisit in SimpleTest
>    ./test_simple.rb:14:in `test_parse'
>
> 1 tests, 0 assertions, 0 failures, 1 errors
>
>
> I then added this method into the simple class above
>
> def return_whatisit
>  @@whatisit
> end
>
>   Then in my test created a Simple object (v = Simple.new) and then
> called the return_whatisit method (eg: v.return_whatisit).     I dont
> really want to have to add extra methods to the code to support the
> retreival of class variables from within the tests.   I dont
> understand why I'm not able to access the class variable @@whatisit
> from within the test script?    Is it possible to extend the Simple
> class from within the test file itself?

The class 'SimpleTest' has nothing to do with your class 'Simple'.  
They share a name but nothing else so you can't access the class  
variable directly.

>   For example iin the test file I would like to add this method to
> the Simple class
> def return_whatisit
>  @@whatisit
> end
>
>   So if you have any tips on how to best approach this situation I
> would appreciate it.    I figure if I get a better understanding of
> using and writing tests that will influence how I write scripts down
> the road.
>
>  TIA. G


The approach you suggest (defining an extra helper method in the test)  
seems to work fine though?

[alexg@powerbook]/Users/alexg/Desktop(6): cat simple.rb
class Simple
   @@whatisit = "false"

   def parse(n)
     @@whatisit = true if n =~ /yes/
   end
end
[alexg@powerbook]/Users/alexg/Desktop(7): cat test.rb
require 'simple'
require 'test/unit'

class Simple
   def return_whatisit
     @@whatisit
   end
end

class SimpleTest <  Test::Unit::TestCase

  def test_parse
    v = Simple.new
    v.parse("yes")

    assert v.return_whatisit
   end

end
[alexg@powerbook]/Users/alexg/Desktop(8): ruby test.rb
Loaded suite test
Started
.
Finished in 0.004223 seconds.

1 tests, 1 assertions, 0 failures, 0 errors

Alex Gutteridge

Bioinformatics Center
Kyoto University