unless (actual `is_close` expected) (assertFailure msg)
where msg = (if null preface then "" else preface ++ "\n") ++
"expected: " ++ show expected ++ "\n but got: " ++ show actual
unless (actual `is_close` expected) (assertFailure msg)
where msg = (if null preface then "" else preface ++ "\n") ++
"expected: " ++ show expected ++ "\n but got: " ++ show actual