I think I must not understand [tcltest].  I love to write tests, but I
find it difficult to compose the correct result values to achieve
null differences.  When I'm off at all, tcltest floods my screen with
more characters than I can digest.  The only way I'm able to cope is
by feeding the stdout from a tcltest run into
    set tmp /tmp/diff[pid]


    set report [read stdin]
    regexp -- {---- Result was:\n(.*?)---- Result should have been:\n(.*)====} \
          $report -> first second
    foreach part {first second} {
        set fp [open $tmp$part w]
        puts -nonewline $fp [set $part]
        close $fp
    }    
    catch {exec diff ${tmp}first ${tmp}second]} result
    puts "Result is:
    $result"

Is there an easier way?