Fix xcmp message processing condition. (#510)

* Fix xcmp message processing condition.

* add a very simple test

* Update Cargo.lock

* remove comment

* remove comment

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: Alexander Popiak <alexander.popiak@gmail.com>

pallets/xcmp-queue/src/tests.rs

@@ -0,0 +1,38 @@
+// Copyright (C) 2021 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use super::*;
+use mock::{new_test_ext, XcmpQueue};
+use cumulus_primitives_core::XcmpMessageHandler;
+
+#[test]
+fn one_message_does_not_panic() {
+	new_test_ext().execute_with(|| {
+		let message_format = XcmpMessageFormat::ConcatenatedVersionedXcm.encode();
+		let messages = vec![
+			(
+				Default::default(),
+				1u32.into(),
+				message_format.as_slice(),
+			),
+		];
+
+		// This shouldn't cause a panic
+		XcmpQueue::handle_xcmp_messages(
+			messages.into_iter(),
+			Weight::max_value(),
+		);
+	})
+}