module ActiveSupport::Testing::Deprecation

def assert_not_deprecated(deprecator = nil, &block)

end
CustomDeprecator.warn "message" # passes assertion, different deprecator
assert_not_deprecated(ActiveSupport::Deprecation.new) do

end
CustomDeprecator.warn "message" # fails assertion
assert_not_deprecated(CustomDeprecator) do

Asserts that no deprecation warnings are emitted by the given deprecator during the execution of the yielded block. 
def assert_not_deprecated(deprecator = nil, &block)
  unless deprecator
    ActiveSupport.deprecator.warn("assert_not_deprecated without a deprecator is deprecated")
    deprecator = ActiveSupport::Deprecation._instance
  end
  result, deprecations = collect_deprecations(deprecator, &block)
  assert deprecations.empty?, "Expected no deprecation warning within the block but received #{deprecations.size}: \n  #{deprecations * "\n  "}"
  result
end