A matcher to assert an array is sorted according to the value of the method or key corresponding to a symbol.

be_ordered_by.rb

# A matcher to assert an array is sorted 
# according to the value of the method or key corresponding to a symbol.
# 
# Looks like this:
# expect([{ :id => 1 }, {:id => 0}]).to be_ordered_by(:id)
# expect([<User>, <User>]).to be_ordered_by(:id)

RSpec::Matchers.define :be_ordered_by do |sort_method|
  match do |actual|
    actual = ensure_sendable(actual)

    expected_order = actual.sort { |x, y| x.send(sort_method) <=> y.send(sort_method) }
    actual == expected_order
  end

  def ensure_sendable(objects_or_hashes)
    objects_or_hashes.map do |obj|
      obj.class == Hash ? OpenStruct.new(obj) : obj
    end
  end
end