F@cking Mocks? How do they work?

mocks.rb

# Note minitest 2 doesn't run out of assertions so that test case would fail
gem 'minitest', '~> 4'

require 'minitest/unit'
require 'minitest/mock'
require 'minitest/autorun'

def do_nothing_with object
end

def do_something_with object
  object.do_something!
end

class WatMockTest < MiniTest::Unit::TestCase
  def test_if_this_test_fails_you_dont_assert_verify
    mock = MiniTest::Mock.new
    mock.expect :foo, true

    do_nothing_with mock

    assert_raises MockExpectationError do
      mock.verify
    end
  end

  def test_also_mocks_fails_if_you_send_them_unexpected_methods
    mock = MiniTest::Mock
    #mock.expect(:do_something).never

    assert_raises NoMethodError do
      do_something_with mock
    end
  end

  def test_you_can_use_object_new_for_dont_sent_mocks
    mock = Object.new

    assert_raises NoMethodError do
      do_something_with mock
    end
  end

  def test_yeah_you_dont_need_to_verify_you_run_out_of_assertions
    mock = MiniTest::Mock.new
    mock.expect :do_something!, true

    do_something_with mock

    assert_raises MockExpectationError do
      do_something_with mock
    end
  end
end