class RSpec::Expectations::BlockExpectationTarget

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