[PATCH v2] merge-base: add tests for --is-ancestor

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
    
    Changes since v1, per review:
    
     * Reuse the E---D---C---B---A history and the G/H merges from the "set
       up G and H" test instead of creating a separate repository.
     * Add a test that --is-ancestor requires exactly two commits: too few
       is a usage error (exit 129), while more than two is rejected with
       "--is-ancestor takes exactly two commits" (exit 128).

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2186%2Fnikolauspschuetz%2Ft6010-test-is-ancestor-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2186/nikolauspschuetz/t6010-test-is-ancestor-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/2186

Range-diff vs v1:

 1:  e512e35788 ! 1:  319bf89d25 merge-base: add tests for --is-ancestor
     @@ t/t6010-merge-base.sh: test_expect_success 'merge-base --octopus --all for compl
       	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 with an ancestor and a descendant' '
     ++	git merge-base --is-ancestor $E $A &&
     ++	test_expect_code 1 git merge-base --is-ancestor $A $E
      +'
      +
     -+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 treats a commit as its own ancestor' '
     ++	git merge-base --is-ancestor $A $A
      +'
      +
     -+test_expect_success '--is-ancestor self' '
     -+	git -C is-ancestor merge-base --is-ancestor two two
     ++test_expect_success '--is-ancestor with diverged commits' '
     ++	test_expect_code 1 git merge-base --is-ancestor $G $H &&
     ++	test_expect_code 1 git merge-base --is-ancestor $H $G
      +'
      +
     -+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 exits 128 on a bad commit' '
     ++	test_expect_code 128 git merge-base --is-ancestor $A no-such-commit &&
     ++	test_expect_code 128 git merge-base --is-ancestor no-such-commit $A
      +'
      +
     -+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 requires exactly two commits' '
     ++	test_expect_code 129 git merge-base --is-ancestor &&
     ++	test_expect_code 129 git merge-base --is-ancestor $A &&
     ++	test_expect_code 128 git merge-base --is-ancestor $E $A $B 2>err &&
     ++	test_grep ".--is-ancestor takes exactly two commits" err
      +'
      +
      +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_expect_code 128 git merge-base --is-ancestor --all $E $A 2>err &&
      +	test_grep "options .--is-ancestor. and .--all. cannot be used together" err
      +'
      +

 t/t6010-merge-base.sh | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)