[PATCH v2 3/4] t: test failed "stash apply --index"

["D. Ben Knoble" <ben.knoble@gmail.com>]

The next commit will refactor index handling for applied stashes, so
let's make sure we cover conflicted index merging, too.

Signed-off-by: D. Ben Knoble <ben.knoble@gmail.com>
---
 t/t3903-stash.sh | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 721158606f..3958ab3c8d 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -374,6 +374,24 @@ setup_stash() {
 	test_cmp expect actual
 '
 
+test_expect_success 'stash apply --index leaves everything untouched on failure' '
+	git reset --hard &&
+	echo test >other-file &&
+	git add other-file &&
+	git stash &&
+	echo unrelated >file &&
+	echo unrelated >another-file &&
+	git add another-file &&
+	git diff-files >expect &&
+
+	echo conflict >other-file &&
+	git add other-file &&
+	test_must_fail git stash apply --index 2>err &&
+	test_grep "conflicts in index. Try without --index" err &&
+	git diff-files >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'stash -k' '
 	echo bar3 >file &&
 	echo bar4 >file2 &&
-- 
2.56.0.rc1.315.gc6ed9934b7.dirty