My current favourite vim trick when writing tests in Perl is CTRL-A.
My tests contain a line near the top that looks like
use Test::More tests => 12 where my test suite has 12 tests. I move my cursor over the number 12 and type
mc which sets a mark labelled "c" for test count.
Then, if I write 5 new tests, I type
`c (backtick c) to jump to my test count, then
5 CTRL-A to increment my test count by 5. Finally,
`` (2 backticks) takes me back to where I was last editing.
If I remove tests, I use CTRL-V instead of CTRL-A to decrement the test count.