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>