safer stubs

s_stub.rb

module RSpec::Mocks::Methods
  # Validates the method exists on the stub-ee before stubbing
  def s_stub(message_or_hash, opts={}, &block)
    if Hash === message_or_hash
      message_or_hash.each {|message, value| s_stub(message).and_return value }
    else
      raise "#{message_or_hash} not defined on #{self.inspect}" unless self.respond_to?(message_or_hash.to_sym)
      stub(message_or_hash.to_sym, opts, &block)
    end
  end

  def s_should_receive(message, opts={}, &block)
    raise "#{message} not defined on #{self.inspect}" unless self.respond_to?(message.to_sym)
    should_receive(message, opts, &block)
  end
end

usage.rb

class Cat
  def meow
    p "Moew!"
  end
end

describe Cat do
  it "woofs" do
    c = Cat.new
    c.s_stub(:woof => "woof") # throws error
    c.woof
  end
  
  it "guffaws" do
    c = Cat.new
    c.s_should_receive(:guffaw).with(:loudly) { "guffaw" } # throws error
    c.guffaw
  end
  
  it "meows" do
    c = cat.new
    c.s_should_receive(:meow) { "Meow" } # works
    c.meow
  end
end