Attempt at converting lambdas to have proc behavior

as_proc.rb

require 'test/unit/testcase'
require 'test/unit' if $0 == __FILE__

class Proc
  
  def as_proc
    if arity == -1
      self 
    else
      aty = arity.abs - (arity < 0 ? 1 : 0)
      proc{|*a| self[*a.values_at(*0...aty)] }
    end
  end

end

class AsProcTest < Test::Unit::TestCase

  def test_fewer_values
    assert_nothing_raised do
      lambda{|a,b,c| }.as_proc[1,2]
    end
    assert_equal [1,2,nil], lambda{|a,b,c| [a,b,c] }.as_proc[1,2]
  end

  def test_variable_args
    assert_nothing_raised do
      lambda{|*a| }.as_proc[1,2,3,4]
    end
    assert_equal [1,2,3], lambda{|*a| a}.as_proc[1,2,3]
    # In Ruby 1.8, procs become lambda-y if given a splat arg
    if RUBY_VERSION.to_f >= 1.9
      assert_nothing_raised do
        lambda{|a,b,*c| }.as_proc[1]
      end
      assert_equal [1,nil,[]], proc{|a,b,*c| [a,b,c] }[1]
      assert_equal [1,nil,[]], lambda{|a,b,*c| [a,b,c] }.as_proc[1]
    end
  end

end