[PATCH v4] t6030: add test for git bisect skip started with --term* arguments

[Bagas Sanjaya <bagasdotme@gmail.com>]

Trygve Aaberge reported git bisect breakage when the bisection
is started with --term* arguments (--term-new and --term-old).

For example, suppose that we have repository with 10 commits, and we
start the bisection from HEAD to first commit (HEAD~9) with:

  $ git bisect start --term-new=fixed --term-old=unfixed HEAD HEAD~9

The bisection then stopped at HEAD~5 (fifth commit), and we choose
to skip (git bisect skip). The HEAD should now at HEAD~4 (sixth commit).
In the breakage, however, the HEAD after skipping stayed at HEAD~5
(not changed). The breakage is caused by forgetting to read '.git/BISECT_TERMS' during implementation of `'bisect skip' subcommand in C.

The fix is in commit 002241336f (bisect--helper: use BISECT_TERMS in
'bisect skip' command, 2021-04-25). To verify it fixes the breakage, add
the test.

Reported-by: Trygve Aaberge <trygveaa@gmail.com>
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
---
  Changes from v3 [1]:
    * Lowercase local name variable hash_skipped_from and hash_skipped_to.
      Christian Couder and Eric Sunshine argued that uppercase local
      variable names make the reader confused them with global
      variables.
    * Mention breakage fix commit 002241336f in the commit message.

  [1]:
https://lore.kernel.org/git/20210428113805.109528-1-bagasdotme@gmail.com/

 t/t6030-bisect-porcelain.sh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
index 32bb66e1ed..a1baf4e451 100755
--- a/t/t6030-bisect-porcelain.sh
+++ b/t/t6030-bisect-porcelain.sh
@@ -922,6 +922,17 @@ test_expect_success 'bisect start takes options and revs in any order' '
 	test_cmp expected actual
 '
 
+# Bisect is started with --term-new and --term-old arguments,
+# then skip. The HEAD should be changed.
+test_expect_success 'bisect skip works with --term*' '
+	git bisect reset &&
+	git bisect start --term-new=fixed --term-old=unfixed HEAD $HASH1 &&
+	hash_skipped_from=$(git rev-parse --verify HEAD) &&
+	git bisect skip &&
+	hash_skipped_to=$(git rev-parse --verify HEAD) &&
+	test "$hash_skipped_from" != "$hash_skipped_to"
+'
+
 test_expect_success 'git bisect reset cleans bisection state properly' '
 	git bisect reset &&
 	git bisect start &&

base-commit: 311531c9de557d25ac087c1637818bd2aad6eb3a
-- 
2.25.1