merge-base: add tests for --is-ancestor

`git merge-base --is-ancestor A B` is used a lot in scripts but has no tests. Add some to t6010 covering its exit codes: 0 when A is an ancestor of B, 1 when it is not, and 128 (not 1) when given a bad argument. Also check that --is-ancestor and --all can't be combined, and that the resulting error names both options. Signed-off-by: Nikolaus Schuetz <nikolauspschuetz@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Nikolaus Schuetz committed Jul 30, 2026 at 06:19 UTC 89454a60ed3c668aabdc372327207096c9613e56
1 file changed +31
t/t6010-merge-base.sh
+31
@@ -305,4 +305,35 @@ test_expect_success 'merge-base --octopus --all for complex tree' '
305 test_cmp expected actual
306 '
307
308 +test_expect_success '--is-ancestor with an ancestor and a descendant' '
309 + git merge-base --is-ancestor $E $A &&
310 + test_expect_code 1 git merge-base --is-ancestor $A $E
311 +'
312 +
313 +test_expect_success '--is-ancestor treats a commit as its own ancestor' '
314 + git merge-base --is-ancestor $A $A
315 +'
316 +
317 +test_expect_success '--is-ancestor with diverged commits' '
318 + test_expect_code 1 git merge-base --is-ancestor $G $H &&
319 + test_expect_code 1 git merge-base --is-ancestor $H $G
320 +'
321 +
322 +test_expect_success '--is-ancestor exits 128 on a bad commit' '
323 + test_expect_code 128 git merge-base --is-ancestor $A no-such-commit &&
324 + test_expect_code 128 git merge-base --is-ancestor no-such-commit $A
325 +'
326 +
327 +test_expect_success '--is-ancestor requires exactly two commits' '
328 + test_expect_code 129 git merge-base --is-ancestor &&
329 + test_expect_code 129 git merge-base --is-ancestor $A &&
330 + test_expect_code 128 git merge-base --is-ancestor $E $A $B 2>err &&
331 + test_grep ".--is-ancestor takes exactly two commits" err
332 +'
333 +
334 +test_expect_success '--is-ancestor and --all cannot be used together' '
335 + test_expect_code 128 git merge-base --is-ancestor --all $E $A 2>err &&
336 + test_grep "options .--is-ancestor. and .--all. cannot be used together" err
337 +'
338 +
339 test_done