class RSpec::Expectations::BlockExpectationTarget

value of the block rather than the block itself.
use a block thinking the expectation will be on the return
expectations, in order to avoid user confusion when they
Validates the provided matcher to ensure it supports block
@private

def enforce_block_expectation(matcher) 

def enforce_block_expectation(matcher)
  return if supports_block_expectations?(matcher)
  raise ExpectationNotMetError, "You must pass an argument rather than a block to `expect` to use the provided " \
    "matcher (#{RSpec::Support::ObjectFormatter.format(matcher)}), or the matcher must implement " \
    "`supports_block_expectations?`."
end

def not_to(matcher, message=nil, &block) 

def not_to(matcher, message=nil, &block)
  enforce_block_expectation(matcher)
  super
end

def supports_block_expectations?(matcher) 

def supports_block_expectations?(matcher)
  matcher.respond_to?(:supports_block_expectations?) && matcher.supports_block_expectations?
end

def to(matcher, message=nil, &block) 

def to(matcher, message=nil, &block)
  enforce_block_expectation(matcher)
  super
end