From: Richard <RichardDummyMailbox58407@...>
Date: 2006-12-04T08:55:08+09:00
Subject: Re: Why does a test fail when I predicted it's exception class?

Hi Eric,

Thanks for weighing in on my question.

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

I like the additions here a lot:
1. Capturing the exception object
2. Checking not only the correct exception type is raised but also
checking the programmed message passed to 'raise'

> def test_eval_bad_operator
1.  I take it that to conform to unit-test's expectations,  the test
names should begin with test_ and not test1_, test2_ etc.

2.  How about me using test_1_Whatever, test_2_SomethingElse, etc,?
Wouldn't that conform equally well and cause any error msgs produced by
Test to be presented in lexicographical order (with fewer than 10
tests; double digits if I wanted up to 99 tests, etc.)?

3.  I like to produce tests in one-line format if they'll fit on my
screen reasonably so that I can write and scan them more quickly.  Do
see any substantive problem in my continuing to do that?

> $ ruby test_polish.rb -n /eval/

I'm running Ruby_1.8.2-15 over WinXP-Pro/SP2.  I tried this command and
got nothing:

=== Command Window ====
K:\_Projects\Ruby\TestUnitTesting\ReversePolishEvaluator>ruby
RevPolishEvaluator.rb -n /eval/

K:\_Projects\Ruby\TestUnitTesting\ReversePolishEvaluator>
====== end ============

I thought the problem might be that I had no errors, so that there was
nothing for Test to report.  So I introduced an erroneous assertion
(expressed  in three lines rather than my preferred one-line format)
but still got nothing.

Then I ran this expanded test through SciTE and got (both in one-line
format as well as three-line format):

==== SciTE output ====
>ruby RevPolishEvaluatorTest.rb
Loaded suite RevPolishEvaluatorTest
Started
.............F....
Finished in 0.031 seconds.

  1) Failure:
test_5_dummy(ErrorTests) [./tc_TestSet2.rb:12]:
<1> expected but was
<2>.

18 tests, 18 assertions, 1 failures, 0 errors
>Exit code: 1
=== end ===

Do you have any idea why the command with the "-n" switch failed on my
system?  My code follows.

Again,  thanks for your suggestions.  I look forward to your comments.

Best wishes,
Richard

=== RevPolishEvaluator.rb ===
### Code same as posted earlier
=== end ===

=== RevPolishEvaluatorTest.rb ===
# Reverse-Polish Evaluation Test

require 'test/unit'
require 'tc_TestSet1'        # <= 13 tests that produced no errors;
file not shown here
require 'tc_TestSet2'
=== end ===

=== tc_TestSet2.rb ===
 require '.\RevPolishEvaluator.rb'

class ErrorTests < Test::Unit::TestCase # The succinct way
	def test_1_noarg; assert_raise(ArgumentError) {Polish.new().eval}; end
	def test_2_badop; assert_raise(ArgumentError) {Polish.new(%w{2 3 $ 7
-- *}).eval}; end
	def test_3_missingdata
		e = assert_raise(ArgumentError) {Polish.new(%w{2 +}).eval}
		assert_equal('Stack underflow', e.message)                          #
<= Had to change the msg to confirm to my coding
	end
	def test_4_divby0; assert_raise(ZeroDivisionError) {Polish.new(%w{2 0
/}).eval}; end
	def test_5_dummy
		assert_equal(1, 2)
	end
end
=== end ===

Eric Hodel wrote:
> 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!