svn mergeinfo — Query merge-related information. See the section called “Mergeinfo and Previews” for details.
Query information related to merges (or potential
            merges) between SOURCE-URL and
            TARGET.  If
            the --show-revs option is not provided,
            display revisions which have been merged
            from SOURCE-URL
            to TARGET.  Otherwise, display
            either merged
            or eligible revisions as specified by
            the --show-revs option.
Find out which changesets your have been merged from your trunk directory into your test branch:
$ svn propget svn:mergeinfo ^/branches/test /branches/other:3-4 /trunk:11-13,14,16 $ svn mergeinfo --show-revs merged ^/trunk ^/branches/test r11 r12 r13 r14 r16 $
Note that the default output from the svn
            mergeinfo command is to display merged revisions, so
            the --show-revs option shown in the
            command line of the previous example is not strictly
            required.
Find out which changesets from your trunk directory have not yet been merged into your test branch:
$ svn mergeinfo --show-revs eligible ^/trunk ^/branches/test r15 r17 r20 r21 r22 $