update-index: add --show-index-version

"git update-index --index-version N" is used to set the index format
version to a specific version, but there was no way to query the
current version used in the on-disk index file.

Teach the command a new "--show-index-version" option, and also
teach the "--index-version N" option to report what the version was
when run with the "--verbose" option.

Helped-by: Linus Arver <linusa@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/t/t2107-update-index-basic.sh b/t/t2107-update-index-basic.sh
index 89b285fa3a..22f4c92399 100755
--- a/t/t2107-update-index-basic.sh
+++ b/t/t2107-update-index-basic.sh
@@ -111,4 +111,35 @@ test_expect_success '--chmod=+x and chmod=-x in the same argument list' '
 	test_cmp expect actual
 '
 
+test_expect_success '--index-version' '
+	git commit --allow-empty -m snap &&
+	git reset --hard &&
+	git rm -f -r --cached . &&
+
+	# The default index version is 2 --- update this test
+	# when you change it in the code
+	git update-index --show-index-version >actual &&
+	echo 2 >expect &&
+	test_cmp expect actual &&
+
+	# The next test wants us to be using version 2
+	git update-index --index-version 2 &&
+
+	git update-index --index-version 4 --verbose >actual &&
+	echo "index-version: was 2, set to 4" >expect &&
+	test_cmp expect actual &&
+
+	git update-index --index-version 4 --verbose >actual &&
+	echo "index-version: was 4, set to 4" >expect &&
+	test_cmp expect actual &&
+
+	git update-index --index-version 2 --verbose >actual &&
+	echo "index-version: was 4, set to 2" >expect &&
+	test_cmp expect actual &&
+
+	# non-verbose should be silent
+	git update-index --index-version 4 >actual &&
+	test_must_be_empty actual
+'
+
 test_done