Toy stub framework with Ruby

test-stub.rb

# Playing around with a Toy Stubbing "framework"
class Statistics
  def initialize(nums)
    @nums = nums
  end

  def compute_average
    sum = 0;
    @nums.each do |num|
      sum += num
    end
    sum.to_f / @nums.length
  end
end

class StubbedStats < Statistics
  methods_to_stub = (instance_methods - Object.instance_methods)
  methods_to_stub.each { |m| undef_method m unless m =~ /(^__|^send$|^object_id$)/ }

  def initialize(*args)
    @canned_responses = {}
  end

  def method_missing(m, *args, &block)
    if @canned_responses.has_key?(m)
      @canned_responses[m]
    else
      raise "Unstubbed method!"
    end
  end

  def canned(m, ret)
    @canned_responses[m] = ret
  end
end

s = StubbedStats.new
# s.is_a? Statistics => true
s.canned(:compute_average, 6.5)
p "The average is: #{s.compute_average}"