[PATCH v2 1/2] diff: add test for --no-index executed outside repo

[Thomas Gummerer <t.gummerer@gmail.com>]

470faf9 diff: move no-index detection to builtin/diff.c breaks the error
message for "git diff --no-index", when the command is executed outside
of a git repository and the wrong number of arguments are given. 6df5762
diff: don't read index when --no-index is given fixes the problem.

Add a test to guard against similar breakages in the future.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---

> Perhaps use CEILING, like this (untested)?

Thanks, this makes sense, here is the new version.

 t/t4053-diff-no-index.sh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
index 077c775..2ab3c48 100755
--- a/t/t4053-diff-no-index.sh
+++ b/t/t4053-diff-no-index.sh
@@ -44,4 +44,15 @@ test_expect_success 'git diff outside repo with broken index' '
 	)
 '
 
+test_expect_success 'git diff --no-index executed outside repo gives correct error message' '
+	(
+		GIT_CEILING_DIRECTORIES=$TRASH_DIRECTORY/non &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_must_fail git diff --no-index a 2>actual.err &&
+		echo "usage: git diff --no-index <path> <path>" >expect.err &&
+		test_cmp expect.err actual.err
+	)
+'
+
 test_done
-- 
1.8.5.4.g8639e57