Why does the <count> escape sequence insert the current line number in my user command?

Question

I've added the following to my .vimrc in order to test how <count> works in a user defined command because I was noticing odd behaviour:

:command! -count=1 CountTest :exe "echo " . <count> . "'" 
noremap <space> :CountTest<cr>

Now, when I type :3CountTest I get what I would expect, i.e., the number 3 is echoed into the prompt. However, when I try using my custom mapping to <space> (i.e. typing 3<space>) I get 3 + the current line number.

I'm sure it's just a problem with the way I've assigned my custom mapping. Any ideas?

Answer 1

In :h map-examples, it is mentioned that

When you type a count before triggering a mapping, it's like the count was typed before the {lhs}.

For your mapping, this means that the count is added before :. This means the actual command that is getting executed is, for count of 2:

:.,.+1CountTest

and for count of 5:

.,.+4CountTest

And the result of what you see is just how range given to a command which should take a count is handled. To handle the count correctly in the mapping, you can use

:nnoremap <space> :<C-u>exec v:count1 "CountTest"<CR>