companion for paritytech/polkadot#3507 (paritytech#1067)

* better test

* fmt

Co-authored-by: Svyatoslav Nikolsky <[email protected]>

Author: gui1117

modules/dispatch/src/lib.rs

@@ -599,9 +599,14 @@ mod tests {
 	fn should_fail_on_weight_mismatch() {
 		new_test_ext().execute_with(|| {
 			let id = [0; 4];
-			let mut message =
-				prepare_root_message(Call::System(<frame_system::Call<TestRuntime>>::remark(vec![1, 2, 3])));
+			let call = Call::System(<frame_system::Call<TestRuntime>>::remark(vec![1, 2, 3]));
+			let call_weight = call.get_dispatch_info().weight;
+			let mut message = prepare_root_message(call);
 			message.weight = 7;
+			assert!(
+				call_weight != 7,
+				"needed for test to actually trigger a weight mismatch"
+			);
 
 			System::set_block_number(1);
 			let result = Dispatch::dispatch(SOURCE_CHAIN_ID, TARGET_CHAIN_ID, id, Ok(message), |_, _| unreachable!());
@@ -615,7 +620,7 @@ mod tests {
 					event: Event::Dispatch(call_dispatch::Event::<TestRuntime>::MessageWeightMismatch(
 						SOURCE_CHAIN_ID,
 						id,
-						1038000,
+						call_weight,
 						7,
 					)),
 					topics: vec![],