stash: add test for the create command line arguments

Currently there is no test showing the expected behaviour of git stash
create's command line arguments.  Add a test for that to show the
current expected behaviour and to make sure future refactorings don't
break those expectations.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3903-stash.sh

@@ -784,4 +784,22 @@ test_expect_success 'push -m shows right message' '
 	test_cmp expect actual
 '
 
+test_expect_success 'create stores correct message' '
+	>foo &&
+	git add foo &&
+	STASH_ID=$(git stash create "create test message") &&
+	echo "On master: create test message" >expect &&
+	git show --pretty=%s -s ${STASH_ID} >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'create with multiple arguments for the message' '
+	>foo &&
+	git add foo &&
+	STASH_ID=$(git stash create test untracked) &&
+	echo "On master: test untracked" >expect &&
+	git show --pretty=%s -s ${STASH_ID} >actual &&
+	test_cmp expect actual
+'
+
 test_done