There is no official protocol for testing fixtures, but it can be done in the following ways. For a lavatory and kitchen sink faucets and showers, simply fill a bucket for 60 seconds. For wall-mounted urinals and water closets, ask the building engineer to assist you in disconnecting the plumbing from the flushometer and measure a flush of water into a bucket. It is recommended that each fixture be tested at least three times, to get a weighted average flow/flush rate. This is quite a process, so consider it a last resort if the fixture documentation can absolutely not be found. Make sure to track all of your testing data in a well-organized spreadsheet and to upload that data to LEED Online, along with a detailed narrative describing your testing methodology.