[PATCH v3] t6030: add test for git bisect skip started with --term* arguments

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.

Let's add the test to catch the breakage. Now that the corresponding
fix had been integrated, flip the switch to test_expect_success.

Reported-by: Trygve Aaberge <redacted>
Signed-off-by: Bagas Sanjaya <redacted>
---

 Changes from v2 [1]:
   * remove double quotes inside test name
   * double-quote HASH_SKIPPED_FROM and HASH_SKIPPED_TO in the
     test comparison line
   * rename test name to be simpler
   * commit message now includes proper explanation why git bisect skip
     is currently broken
   * because the fix to the breakage had just been landed on seen, flip
     the switch to test_expect_success.
   * give credit to Trygve in form of Reported-by

[1]: https://lore.kernel.org/git/20210425080508.154159-1-bagasdotme@gmail.com/ (local)

 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..ca3a1de433 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