how can i test my golf trolley battery?

I take this that you just bought a new battery and not purchased the whole unit, buggy I mean.

First thing is if in UK (this being world wide forum) type in your search engine 'Sale of goods act' access the site and look up consumer rights. Get info under your belt. Either return to the seller with that info or get auto electricians report on the battery, tested in static state and under load ie;while moving, so ensure it's charged up.
If the tests show it's the battery you have a good case for replacement and claim for testing.
Hopefully you purchased the correct battery for the buggy if not you have no case I'm afraid.
Hope this helps.

Bob
October 2010