console

> ruby -rmath_functions.rb -e "puts MathFunctions.factorial(2)"
2
 
> ruby --test -rmath_functions.rb
 
.
 
Finished in 1.000706 seconds.
 
1 tests, 2 assertions, 0 failures, 0 errors

math_functions.rb

module MathFunctions
  def self.factorial(n)
    (1..n).inject(1) { |acc, x| acc * x}
  end
end

=begin :unittest

assert MathFunctions.factorial(6) == 720
assert MathFunctions.factorial(5) == 120

=end

FYI, I have restructured stuff and started writing a simple gem and added some examples using rspec.

Not sure how this will end up. Here is the repo http://github.com/jeroenvandijk/inline_tests