From: Eric Hodel <drbrain@...7.net>
Date: 2006-12-03T18:58:00+09:00
Subject: Re: Why does a test fail when I predicted it's exception class?

On Dec 2, 2006, at 20:40 , Richard wrote:
> You guys were right on!  Below is one of my actual test sets, the one
> with the exception testing.  It is more complicated than the toy I
> posted, so it took me a few syntax-errors to get it to work.  But then
> I got my desired: 17 tests, 17 assertions, 0 failures, 0 errors
>
>  require '.\RevPolishEvaluator.rb'
>
> class ErrorTests < Test::Unit::TestCase # The succinct way
> 	def test1_noarg; assert_raise(ArgumentError) {Polish.new().eval}; end
> 	def test2_badop; assert_raise(ArgumentError) {Polish.new(%w{2 3 $  
> 7 --
> *}).eval}; end
> 	def test3_missingdata; assert_raise(ArgumentError) {Polish.new(%w{2
> +}).eval}; end
> 	def test4_divby0; assert_raise(ZeroDivisionError) {Polish.new(%w{2 0
> /}).eval}; end
> end

Better:

require 'test/unit'
require 'rev_polish_evaluator'

class TestPolish < Test::Unit::TestCase

   def test_eval_bad_operator
     # ...
   end

   def test_eval_divide_by_zero
     # ...
   end

   def test_eval_no_input
     e = assert_raise ArgumentError do Polish.new.eval end
     assert_equal 'no arguments supplied', e.message
   end

   def test_eval_missing_data
     # ...
   end

end

Written this way your tests:

* follow the test/unit naming scheme (TestBlah where Blah is the  
class you're testing)
* be in the same order as the output (alphabetical)
* will work with the -n flag:

   $ ruby test_polish.rb -n /eval/

* will work with testrb:

   $ testrb .

-- 
Eric Hodel - drbrain@segment7.net - http://blog.segment7.net

I LIT YOUR GEM ON FIRE!