Re: [PATCH] revision: fix --left/right-only use with unrelated histories

On Sun Mar 30, 2025 at 6:11 AM EDT, Phillip Wood wrote:

Thank you for adding a test. We have a helper function test_line_count 
which provides a helpful debugging message if the comparison fails. 
Using that and avoiding process substitutions we'd write

	sort head >sorted_head &&
	sort cmp >sorted_cmp &&
	comm -12 sorted_head sorted_cmp >actual &&
	test_line_count = 0 actual

Thanks for that helper tip.  I was just about to send a v2 when your
message came in, so I'm getting that incorporated now.

By the way, I had originally wanted to write test assertions that
checked the actual number of commit ids returned from each of the two
calls to rev-list - something like:

    git rev-list --X-only HEAD...cmp >file &&
    test_line_count = N file

But since I'm not very familiar with this test harness yet, I couldn't
actually figure the correct value for N.  It's not 1 (the commit made in
my test body), and it's not 2 (that commit, plus the one from the setup
case at the top of the file).  Any appropriate higher value wasn't
obvious.

So I switched to what you saw in my v1.  Maybe this "no commit ids in
common" test is actually the stronger assertion?