class RSpec::Matchers::BuiltIn::YieldProbe

the yield behavior of the object-under-test.
yield matchers is used. Provides information about
Object that is yielded to ‘expect` when one of the
@private

def self.probe(block, &callback) 

def self.probe(block, &callback)
  probe = new(block, &callback)
  return probe unless probe.has_block?
  probe.probe
end

def assert_used! 

def assert_used!
  return if @used
  raise 'You must pass the argument yielded to your expect block on ' \
        'to the method-under-test as a block. It acts as a probe that ' \
        'allows the matcher to detect whether or not the method-under-test ' \
        'yields, and, if so, how many times, and what the yielded arguments ' \
        'are.'
end

def assert_valid_expect_block! 

def assert_valid_expect_block!
  block_signature = RSpec::Support::BlockSignature.new(@block)
  return if RSpec::Support::StrictSignatureVerifier.new(block_signature, [self]).valid?
  raise 'Your expect block must accept an argument to be used with this ' \
        'matcher. Pass the argument as a block on to the method you are testing.'
end

def assert_valid_expect_block!

the `assert_used!` error message from above, which is sufficient.
when the user forgets to accept an arg in their block. They'll still get
It's OK to skip, this, though; it just provides a nice error message
so we can't distinguish between accepting no args and an arg splat.
On 1.8.7, `lambda { }.arity` and `lambda { |*a| }.arity` both return -1,
:nocov: 
def assert_valid_expect_block!
  # nothing to do
end

def has_block? 

def has_block?
  Proc === @block
end

def initialize(block, &callback) 

def initialize(block, &callback)
  @block = block
  @callback = callback || Proc.new {}
  @used = false
  self.num_yields = 0
  self.yielded_args = []
end

def probe 

def probe
  assert_valid_expect_block!
  @block.call(self)
  assert_used!
  self
end

def single_yield_args 

def single_yield_args
  yielded_args.first
end

def to_proc 

def to_proc
  @used = true
  probe = self
  callback = @callback
  Proc.new do |*args|
    probe.num_yields += 1
    probe.yielded_args << args
    callback.call(*args)
    nil # to indicate the block does not return a meaningful value
  end
end

def yielded_once?(matcher_name) 

def yielded_once?(matcher_name)
  case num_yields
  when 1 then true
  when 0 then false
  else
    raise "The #{matcher_name} matcher is not designed to be used with a " \
          'method that yields multiple times. Use the yield_successive_args ' \
          'matcher for that case.'
  end
end