class RSpec::Matchers::BuiltIn::ChangeFromValue

(and, optionally, to a specific value).
Used to specify a change from a specific value
@api private

def change_description 

def change_description
  "from #{description_of @expected_before}#{@description_suffix}"
end

def does_not_match?(event_proc)

Other tags:
    Private: - 
def does_not_match?(event_proc)
  if @description_suffix
    raise NotImplementedError, "`expect { }.not_to change { }.to()` " \
      "is not supported"
  end
  perform_change(event_proc) && !@change_details.changed? && @matches_before
end

def failure_message_when_negated

Other tags:
    Private: - 
def failure_message_when_negated
  return not_given_a_block_failure unless Proc === @event_proc
  return before_value_failure unless @matches_before
  did_change_failure
end

def initialize(change_details, expected_before) 

def initialize(change_details, expected_before)
  @description_suffix = nil
  super(change_details, expected_before, MATCH_ANYTHING)
end

def to(value)

Other tags:
    Api: - public 
def to(value)
  @expected_after     = value
  @description_suffix = " to #{description_of value}"
  self
end