require 'rubygems'
require 'spec'

module SpyMatchers
  class MethodRecorder
    def method_missing(sym, *args)
      MethodVerifier.new({sym => args})
    end
  end

  def have_received
    MethodRecorder.new
  end

  class MethodVerifier
    def initialize(expected)
      @expected = expected
    end

    def matches?(target)
      @target = target
      @target.was_method_called?(@expected)
    end

    def failure_message
      "expected #{@target.__subject__.inspect} to have received #{@expected.keys[0]}(#{@expected.values[0]})"
    end

    def negative_failure_message
      "expected #{@target.__subject__.inspect} not to have received #{@expected.keys[0]}(#{@expected.values[0]})"
    end
  end
end

class Spy
  def self.on(subject)
    Spy.new(subject)
  end

  def initialize(subject)
    @subject = subject
    @method_calls = []
  end

  def was_method_called?(method_with_args)
    return @method_calls.include?(method_with_args)
  end

  def __subject__
    @subject
  end

  def method_missing(sym, *args)
    @method_calls << {sym => args}
    @subject.send(sym, *args)
  end
end

describe "ubiquitous assertion syntax" do
  include SpyMatchers

  it "should test state" do
    2.should == 1+1
  end

  it "should test an error" do
    lambda { [].not_a_method }.should raise_error(NoMethodError)
  end

  it "should test behavior" do
    array = Spy.on []
    [1, 2].each do |number|
      array << number
    end
    array.should have_received << 1
    array.should have_received << 2
  end
end