Setup and document proper XCM testing

[justinfrevert]

We don't have a dedicated testing practice in this repo. Trappist will be XCM-heavy, so we should have a documented testing process that works well with XCM.

• Compare methods/frameworks for testing XCM cross-chain
• Implement the process and a few useful/demonstrative tests

[bernardoaraujor]

As I work on #51 the competing strategies I have considered are:

• parachains-integration-tests by @NachoPal
• Unit tests on the pallet source. @arturgontijo pointed out pallet-xcm tests and its mock runtime as references.
• Unit tests via xcm-simulator.

I still haven't decided which route to go down.

[justinfrevert]

Another one to consider(also for the work on this issue) might be Zombienet. It's actively maintained by Parity

[NachoPal]

Another one to consider(also for the work on this issue) might be [Zombienet](I would also be curious about Zombienet. It's actively maintained by Parity

parachains-integration-tests is using zombienet (or polkadot-launch or any other testnet of your choice) as network deployment tool.

[NachoPal]

I might be biased, but I think you'll be able to to write/update/maintain tests much faster and writing much less code using parachains-integration-tests. That was the main goal of the tool, to abstract testing from polkadot-js. Other one was to make it XCM testing friendly.

It is the tool we use for Common Good Parachains. You can find the tests here: https:/paritytech/cumulus/tree/master/parachains/integration-tests

[justinfrevert]

I think parachains-integration-tests looks fine, especially if devs can crop down to a more granular syntax through it, if the yaml is limiting in some scenario. Maybe it's what Custom is for?

[NachoPal]

I think parachains-integration-tests looks fine, especially if devs can crop down to a more granular syntax through it, if the yaml is limiting in some scenario. Maybe it's what Custom is for?

Right, you can always run any test providing a ts/js file.

[bernardoaraujor]

@nukemandan just suggested that wathever strategies we come up here, it might be interesting to have some the learnings distilled into substrate-parachain-template so that the community can also benefit from the learning outcomes.

[stiiifff]

Great idea ! It can also be a good topic for a presentation.

[bernardoaraujor]

@Wiezzel a few ideas on this issue:

• There's a small (and underdocumented) example on how to test the Asset Registry pallet on the integration-tests directory. It's just doing a one-hop reserve transfer (statemint/trappist), but a second test with a two-hop reserve transfer (statemint/trappist/3000) could be added.
• Another idea I had was to test the ink! PoC that Hector added, which would be a cool way to showcase integration of ink! and parachains-integration-tests.
• As part of the solution for XCM Config: Asset trap & claim system #52 I'll be adding another test based on the Asset Trap solution. I'll tag you for review once the PR is ready.

[Wiezzel]

@bernardoaraujor Why did you close the issue?

[bernardoaraujor]

@Wiezzel @stiiifff I must have clicked by mistake! I really didn't meant to close it.
My sincere apologies!

[stiiifff]

Un-assigning @Wiezzel as he is currently busy with other tasks.