class RSpec::Expectations::BlockExpectationTarget

def enforce_block_expectation(matcher)
  return if supports_block_expectations?(matcher)
  RSpec.deprecate("Using a matcher in a block expectation expression " +
                  "(e.g. `expect { }.to matcher`) that does not implement " +
                  "`supports_block_expectations?`",
                  :replacement => "a value expectation expression " +
                  "(e.g. `expect(value).to matcher`) or implement " +
                  "`supports_block_expectations?` on the provided matcher " +
                  "(#{description_of matcher})")
end