[PATCH] merge-base: add tests for --is-ancestor

From: Nikolaus Schuetz via GitGitGadget <gitgitgadget@gmail.com>
Date: Jul 25, 2026, 17:00 UTC
Message-ID: <pull.2186.git.1784998828879.gitgitgadget@gmail.com>

From: Nikolaus Schuetz <nikolauspschuetz@gmail.com>

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

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2186%2Fnikolauspschuetz%2Ft6010-test-is-ancestor-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2186/nikolauspschuetz/t6010-test-is-ancestor-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2186

 t/t6010-merge-base.sh | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/t/t6010-merge-base.sh b/t/t6010-merge-base.sh
index 44c726ea39..d28d9dab2c 100755
--- a/t/t6010-merge-base.sh
+++ b/t/t6010-merge-base.sh
@@ -305,4 +305,38 @@ test_expect_success 'merge-base --octopus --all for complex tree' '
 	test_cmp expected actual
 '
 
+test_expect_success 'setup --is-ancestor' '
+	git init is-ancestor &&
+	(
+		cd is-ancestor &&
+		test_commit one &&
+		test_commit two &&
+		git checkout -b side one &&
+		test_commit three
+	)
+'
+
+test_expect_success '--is-ancestor parent and child' '
+	git -C is-ancestor merge-base --is-ancestor one two &&
+	test_expect_code 1 git -C is-ancestor merge-base --is-ancestor two one
+'
+
+test_expect_success '--is-ancestor self' '
+	git -C is-ancestor merge-base --is-ancestor two two
+'
+
+test_expect_success '--is-ancestor diverged commits' '
+	test_expect_code 1 git -C is-ancestor merge-base --is-ancestor three two
+'
+
+test_expect_success '--is-ancestor exit 128 non-existent commit' '
+	test_expect_code 128 git -C is-ancestor merge-base --is-ancestor one no-such-commit &&
+	test_expect_code 128 git -C is-ancestor merge-base --is-ancestor no-such-commit one
+'
+
+test_expect_success '--is-ancestor and --all cannot be used together' '
+	test_expect_code 128 git -C is-ancestor merge-base --is-ancestor --all one two 2>err &&
+	test_grep "options .--is-ancestor. and .--all. cannot be used together" err
+'
+
 test_done

base-commit: f60db8d575adb79761d363e026fb49bddf330c73

-- 
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