class RSpec::Core::Formatters::DeprecationFormatter::FileStream

def initialize(file)
  @file = file
  # In one of my test suites, I got lots of duplicate output in the
  # deprecation file (e.g. 200 of the same deprecation, even though
  # the `puts` below was only called 6 times). Setting `sync = true`
  # fixes this (but we really have no idea why!).
  @file.sync = true
end