Taylor Blau [off-list ref] writes:

quoted

If the test involved is longer than 3 lines, I would recommend
against it, as "git show" of such a patch will show the full code
change to implement a different behaviour plus "_failure" changing
to "_success" in the test, with the body of the test hidden outside
the context, which makes it hard to guess what the behaviour change
is really about.

Hmm, I am not sure that I agree. Or, at the very least, that is now how
I have written series in the past where I want to demonstrate and then
subsequently fix an existing bug.

After applying and in viewing "git log -W -p", there is no such
difficulty like the one I described in the message you are
responding to, but it makes it harder on reviewers on the mailing
list, to make a quick pre-review based only on the material that
they can see in the e-mail.

It may be easier to write the commits, but given that we seem to
have more patches sent to the list than reviewers can review, it may
not be a good trade-off.