How do I use expect{}.to change().from().to() on Array?

expect_spec.rb

require 'rspec'

class Int
  attr_reader :count
  def initialize
    @count = 0
  end
  def increment
    @count += 1
  end
end

class Ary
  attr_reader :ary
  def initialize
    @count = 0
    @ary = []
  end
  def increment
    @ary << @count
    @count += 1
  end
end

describe Int, "#increment" do
  subject{ Int.new }
  it "should increment the count" do
    expect { subject.increment }.to change(subject, :count).from(0).to(1)
  end

  it "should increment the count by 1" do
    expect { subject.increment }.to change(subject, :count).by(1)
  end
end

describe Ary, "#ary" do
  subject{ Ary.new }
  it "should increment the ary" do
    expect { subject.increment }.to change(subject, :ary).from([0]).to([0,1])
  end

  it "should increment the ary by [1]" do
    expect { subject.increment }.to change(subject, :ary).by([1])
  end
end

# /Users/niku% ruby -v
# ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-darwin10.6.0]
# /Users/niku% rspec --version
# 2.5.1
# /Users/niku% rspec --color --format documentation expect_spec.rb
#
# Int#increment
#   should increment the count
#   should increment the count by 1
#
# Ary#ary
#   should increment the ary (FAILED - 1)
#   should increment the ary by [1] (FAILED - 2)
#
# Failures:
#
#   1) Ary#ary should increment the ary
#      Failure/Error: expect { subject.increment }.to change(subject, :ary).from([0]).to([0,1])
#        ary should have been changed to [0, 1], but is now [0]
#      # ./expect_spec.rb:39:in `block (2 levels) in <top (required)>'
#
#   2) Ary#ary should increment the ary by [1]
#      Failure/Error: expect { subject.increment }.to change(subject, :ary).by([1])
#        ary should have been changed by [1], but was changed by []
#      # ./expect_spec.rb:43:in `block (2 levels) in <top (required)>'
#
# Finished in 0.00117 seconds
# 4 examples, 2 failures

finaly_i_solved_this.rb

require 'rspec'
class Ary
  attr_reader :ary
  def initialize
    @count = 0
    @ary = []
    increment
  end
  def increment
    @ary << @count
    @count += 1
  end
end

describe Ary, "#ary" do
  subject{ Ary.new }
  it "should increment the ary" do
    expect { subject.increment }.to change{ subject.ary.clone }.from([0]).to([0,1])
  end

  it "should increment the ary by [1]" do
    expect { subject.increment }.to change{ subject.ary.clone }.by([1])
  end
end