[GSoC][PATCH v3 0/6] t: port reftable/stack_test.c to the unit testing framework

[Chandra Pratap <chandrapratap3519@gmail.com>]

The reftable library comes with self tests, which are exercised
as part of the usual end-to-end tests and are designed to
observe the end-user visible effects of Git commands. What it
exercises, however, is a better match for the unit-testing
framework, merged at 8bf6fbd0 (Merge branch 'js/doc-unit-tests',
2023-12-09), which is designed to observe how low level
implementation details, at the level of sequences of individual
function calls, behave.

Hence, port reftable/stack_test.c to the unit testing framework and
improve upon the ported test. The first patch in the series moves
the test to the unit testing framework, and the rest of the patches
improve upon the ported test.

Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Chandra Pratap <chandrapratap3519@gmail.com>

---
Changes in v2:
- Use 'size_t' as array index instead of 'int' in a test that is
  modified in patch 2.
- Fix a coding style violation in the newly introduced test in
  patch 6.

CI/PR: https://github.com/gitgitgadget/git/pull/1762

Chandra Pratap(6):
t: move reftable/stack_test.c to the unit testing framework
t: harmonize t-reftable-stack.c with coding guidelines
t-reftable-stack: use Git's tempfile API instead of mkstemp()
t-reftable-stack: use reftable_ref_record_equal() to compare ref records
t-reftable-stack: add test for non-default compaction factor
t-reftable-stack: add test for stack iterators

Makefile                                                 |   2 +-
reftable/reftable-tests.h                                |   1 -
t/helper/test-reftable.c                                 |   1 -
reftable/stack_test.c => t/unit-tests/t-reftable-stack.c | 611 +++++++++++++++++++--------------
4 files changed, 360 insertions(+), 255 deletions(-)

Range-diff against v2:
1:  e172ceefd7 ! 1:  838ccc63a7 t: harmonize t-reftable-stack.c with coding guidelines
    @@ t/unit-tests/t-reftable-stack.c: static void t_reftable_stack_compaction_concurr
      	/* break abstraction boundary to simulate unclean shutdown. */
     -	int i = 0;
     -	for (; i < st->readers_len; i++) {
    -+	for (int i = 0; i < st->readers_len; i++)
    ++	for (size_t i = 0; i < st->readers_len; i++)
      		reftable_reader_free(st->readers[i]);
     -	}
      	st->readers_len = 0;
2:  73b94aaa6a = 2:  2a151c299c t-reftable-stack: use Git's tempfile API instead of mkstemp()
3:  b6f0363656 = 3:  fb5073da2c t-reftable-stack: use reftable_ref_record_equal() to compare ref records
4:  35c09e6054 = 4:  028fa6f70b t-reftable-stack: add test for non-default compaction factor
5:  3163c2af7d ! 5:  fa0d358e65 t-reftable-stack: add test for stack iterators
    @@ t/unit-tests/t-reftable-stack.c: static void t_reftable_stack_add(void)
     +	}
     +
     +	for (i = 0; i < N; i++) {
    -+		err = reftable_stack_add(st, &write_test_ref, &refs[i]);
    ++		err = reftable_stack_add(st, write_test_ref, &refs[i]);
     +		check(!err);
     +	}
     +
    @@ t/unit-tests/t-reftable-stack.c: static void t_reftable_stack_add(void)
     +			.log = &logs[i],
     +			.update_index = reftable_stack_next_update_index(st),
     +		};
    -+		err = reftable_stack_add(st, &write_test_log, &arg);
    ++		err = reftable_stack_add(st, write_test_log, &arg);
     +		check(!err);
     +	}
     +