1. respond_to matcher.rb

class Foo
  def a
  end

  private
    def b
    end
end

Foo.new.should respond_to(:a) # passed
Foo.new.should respond_to(:b) # failed  # 'd like to pass this
Foo.new.should respond_to(:c) # failed

2. provide matcher.rb

Spec::Matchers.define :provide do |expected|
  match do |obj|
    (obj.public_methods + obj.protected_methods + obj.private_methods).include?(expected.to_s)
  end
end

Foo.new.should provide(:a) # passed
Foo.new.should provide(:b) # passed
Foo.new.should provide(:c) # failed