From: Ned Konz <ned@...>
Date: 2002-06-03T11:23:56+09:00
Subject: Re: Does assert() exist?

On Sunday 02 June 2002 06:54 pm, Philip Mak wrote:
> I saw a bunch of Ruby examples on the web that involve the assert()
> method. However, I can't seem to use it. Does this method exist /
> what do I have to do to be able to access it?
>
> irb(main):001:0> assert(true)
> NameError: undefined method `assert' for #<Object:0x401ddce0>
>     from (irb):1

The Test::Unit library defines a number of assert methods, but they're 
only used in test suites, not in regular code.

However, it's not hard to write one. This one is a no-op unless the 
$DEBUG flag is set, which is set by the "-d" command line switch to 
ruby.

----------- assert.rb -----------
class AssertionFailure < StandardError
end

class Object
  def assert(bool, message = 'assertion failure')
    if $DEBUG
      raise AssertionFailure.new(message) unless bool
    end
  end
end
--------- assertTest.rb -----------
require 'assert.rb'
assert(true, "testing true")
assert(false, "testing false")
--------------------------------------
$ ruby assertTest.rb
$ ruby -d assertTest.rb
Exception `AssertionFailure' at ./assert.rb:7 - testing false
./assert.rb:7:in `assert': testing false (AssertionFailure)
        from assertTest.rb:4

-- 
Ned Konz
http://bike-nomad.com
GPG key ID: BEEA7EFE