Re: [PATCH v4 2/9] config tests: add "NULL" tests for *_get_value_multi()

Ævar Arnfjörð Bjarmason  [off-list ref] writes:

A less well known edge case in the config format is that keys can be
value-less, a shorthand syntax for "true" boolean keys. I.e. these two
are equivalent as far as "--type=bool" is concerned:

	[a]key
	[a]key = true

But as far as our parser is concerned the values for these two are
NULL, and "true". I.e. for a sequence like:

	[a]key=x
	[a]key
	[a]key=y

We get a "struct string_list" with "string" members with ".string"
values of:

	{ "x", NULL, "y" }

This behavior goes back to the initial implementation of
git_config_bool() in 17712991a59 (Add ".git/config" file parser,
2005-10-10).

When parts of the config_set API were tested for in [1] they didn't
add coverage for 3/4 of the "(NULL)" cases handled in
"t/helper/test-config.c". We'd test that case for "get_value", but not
"get_value_multi", "configset_get_value" and
"configset_get_value_multi".

We now cover all of those cases, which in turn expose the details of
how this part of the config API works.

Good to see a better coverage.

With the "last one wins" semantics for half of these 4 cases, it may
make sense to further extend the tests to cover cases where the last
one is a valueless true, in addition to what is used in this patch
(i.e. a valueless true in the middle of three).

Thanks.