remote: add tests for add and rename with invalid names

In preparation for a future patch that moves `builtin/remote.c`'s
remote-name validation, ensure `git remote add` and `git remote rename`
report errors when the new name isn't valid.

Signed-off-by: Sean Barag <sean@barag.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 8d62edd..1156f52 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -179,6 +179,13 @@
 	)
 '
 
+test_expect_success 'rename errors out early when when new name is invalid' '
+	test_config remote.foo.vcs bar &&
+	echo "fatal: '\''invalid...name'\'' is not a valid remote name" >expect &&
+	test_must_fail git remote rename foo invalid...name 2>actual &&
+	test_i18ncmp expect actual
+'
+
 test_expect_success 'add existing foreign_vcs remote' '
 	test_config remote.foo.vcs bar &&
 	echo "fatal: remote foo already exists." >expect &&
@@ -194,6 +201,12 @@
 	test_i18ncmp expect actual
 '
 
+test_expect_success 'add invalid foreign_vcs remote' '
+	echo "fatal: '\''invalid...name'\'' is not a valid remote name" >expect &&
+	test_must_fail git remote add invalid...name bar 2>actual &&
+	test_i18ncmp expect actual
+'
+
 cat >test/expect <<EOF
 * remote origin
   Fetch URL: $(pwd)/one