module ActiveSupport::Testing::Deprecation

def assert_deprecated(match = nil, &block)
  result, warnings = collect_deprecations(&block)
  assert !warnings.empty?, "Expected a deprecation warning within the block but received none"
  if match
    match = Regexp.new(Regexp.escape(match)) unless match.is_a?(Regexp)
    assert warnings.any? { |w| w =~ match }, "No deprecation warning matched #{match}: #{warnings.join(', ')}"
  end
  result
end

def assert_not_deprecated(&block)
  result, deprecations = collect_deprecations(&block)
  assert deprecations.empty?, "Expected no deprecation warning within the block but received #{deprecations.size}: \n  #{deprecations * "\n  "}"
  result
end

def collect_deprecations
  old_behavior = ActiveSupport::Deprecation.behavior
  deprecations = []
  ActiveSupport::Deprecation.behavior = Proc.new do |message, callstack|
    deprecations << message
  end
  result = yield
  [result, deprecations]
ensure
  ActiveSupport::Deprecation.behavior = old_behavior
end