config tests: add "NULL" tests for *_get_value_multi()
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.
1.
4c715ebb96a (test-config: add tests for the config_set API,
2014-07-28)
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>