# Note for reviewer
Most changes are just syntax changes necessary for the new version.
Most important files should be the ones under the `xcm` folder.
# Description
Added XCMv4.
## Removed `Multi` prefix
The following types have been renamed:
- MultiLocation -> Location
- MultiAsset -> Asset
- MultiAssets -> Assets
- InteriorMultiLocation -> InteriorLocation
- MultiAssetFilter -> AssetFilter
- VersionedMultiAsset -> VersionedAsset
- WildMultiAsset -> WildAsset
- VersionedMultiLocation -> VersionedLocation
In order to fix a name conflict, the `Assets` in `xcm-executor` were
renamed to `HoldingAssets`, as they represent assets in holding.
## Removed `Abstract` asset id
It was not being used anywhere and this simplifies the code.
Now assets are just constructed as follows:
```rust
let asset: Asset = (AssetId(Location::new(1, Here)), 100u128).into();
```
No need for specifying `Concrete` anymore.
## Outcome is now a named fields struct
Instead of
```rust
pub enum Outcome {
Complete(Weight),
Incomplete(Weight, Error),
Error(Error),
}
```
we now have
```rust
pub enum Outcome {
Complete { used: Weight },
Incomplete { used: Weight, error: Error },
Error { error: Error },
}
```
## Added Reanchorable trait
Now both locations and assets implement this trait, making it easier to
reanchor both.
## New syntax for building locations and junctions
Now junctions are built using the following methods:
```rust
let location = Location {
parents: 1,
interior: [Parachain(1000), PalletInstance(50), GeneralIndex(1984)].into()
};
```
or
```rust
let location = Location::new(1, [Parachain(1000), PalletInstance(50), GeneralIndex(1984)]);
```
And they are matched like so:
```rust
match location.unpack() {
(1, [Parachain(id)]) => ...
(0, Here) => ...,
(1, [_]) => ...,
}
```
This syntax is mandatory in v4, and has been also implemented for v2 and
v3 for easier migration.
This was needed to make all sizes smaller.
# TODO
- [x] Scaffold v4
- [x] Port github.com/paritytech/polkadot/pull/7236
- [x] Remove `Multi` prefix
- [x] Remove `Abstract` asset id
---------
Co-authored-by: command-bot <>
Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>
So far the `bridge-hub-test-utils` contained a tests set for testing
BridgeHub runtime that is bridging with the remote **parachain**. But we
have https://github.com/paritytech/polkadot-sdk/pull/2540 coming, which
would add Rococo <> Bulletin chain bridge (where Bulletin = standalone
chain that is using GRANDPA finality). Then it'll be expanded to
Polkadot BH as well.
So this PR adds the same set of tests to the `bridge-hub-test-utils`,
but for the case when remote chain is the chain with GRANDPA finality.
There's a lot of changes in this PR - I'll describe some:
- I've added `BasicParachainRuntime` trait to decrease number of lines
we need to add to `where` clause. Could revert, but imo it is useful;
- `cumulus/parachains/runtimes/bridge-hubs/test-utils/src/test_data` is
a submodule for generating test data for the test sets.
`from_parachain.rs` is used in tests for the case when remote chain is a
parachain, `from_grandpa_chain.rs` - for the bridges with remote GRANDPA
chains. `mod.rs` has some code, shared by both types of tests;
- `cumulus/parachains/runtimes/bridge-hubs/test-utils/src/test_data` is
a submodule with all test cases. The `mod.rs` has tests, suitable for
all cases. There's also `wth_parachain.rs` and `with_grandpa_chain.rs`
with the same meaning as above;
- I've merged the "core" code of two previous tests -
`relayed_incoming_message_works` and `complex_relay_extrinsic_works`
into one single `relayed_incoming_message_works` test. So now we are
always constructing extrinsics and are dispatching them using executive
module (meaning all signed extensions are also tested).
New test set is used here:
https://github.com/paritytech/polkadot-sdk/pull/2540. Once this PR is
merged, I'll merge that other PR with master to remove duplicate
changes.
I'm also planning to cleanup generic constraints + remove some
unnecessary assumptions about used chains in a follow-up PRs. But for
now I think this PR has enough changes, so don't want to complicate it
even more.
---
Breaking changes for the code that have used those tests before:
- the `construct_and_apply_extrinsic` callback now accepts the
`RuntimeCall` instead of the `pallet_utility::Call`;
- the `construct_and_apply_extrinsic` now may be called multiple times
for the single test, so make sure the `frame_system::CheckNonce` is
correctly constructed;
- all previous tests have been moved from
`bridge_hub_test_utils::test_cases` to
`bridge_hub_test_utils::test_cases::from_parachain` module;
- there are several changes in test arguments - please refer to
https://github.com/paritytech/polkadot-sdk/compare/sv-tests-for-bridge-with-remote-grandpa-chain?expand=1#diff-79a28d4d3e1749050341c2424f00c4c139825b1a20937767f83e58b95166735c
for details.
Francisco Aguirre