A follow-up PR to simplify event assertions by introducing
`contains_event`, allowing event checks without needing exact field
matches. This reduces redundancy and makes tests more flexible.

Partially addresses #6119 by providing an alternative way to assert
events.

Reference: [PR #7594 -
Discussion](https://github.com/paritytech/polkadot-sdk/pull/7594#discussion_r1965566349)

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Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: Bastian Köcher <git@kchr.de>

# Description

This PR introduces a lightweight log-capturing mechanism for XCM unit
tests, simplifying debugging by enabling structured log assertions. It
partially addresses #6119 and #6125, offering an optional way to verify
logs in tests while remaining unobtrusive in normal execution.

# Key Changes

* [x] Introduces a log capture utility in `sp_tracing`.
* [x] Adds XCM test examples demonstrating how and when to use log
capturing.

# Review Notes:

* The log capture mechanism is opt-in and does not affect existing tests
unless explicitly used.
* The implementation is minimal and does not add complexity to existing
test setups.
* It provides a structured alternative to
[`sp_tracing::init_for_tests()`](https://paritytech.github.io/polkadot-sdk/master/sp_tracing/fn.init_for_tests.html)
for log verification in automated tests.

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Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Closes: https://github.com/paritytech/polkadot-sdk/issues/6585

Removing the `require_weight_at_most` parameter in V5 Transact had only
one problem. Converting a message from V5 to V4 to send to chains that
didn't upgrade yet. The conversion would not know what weight to give to
the Transact, since V4 and below require it.

To fix this, I added back the weight in the form of an `Option<Weight>`
called `fallback_max_weight`. This can be set to `None` if you don't
intend to deal with a chain that hasn't upgraded yet. If you set it to
`Some(_)`, the behaviour is the same. The plan is to totally remove this
in V6 since there will be a good conversion path from V6 to V5.

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Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Adrian Catangiu <adrian@parity.io>

# Context

This PR aims to introduce XCMv5, for now it's in progress and will be
updated over time.
This branch will serve as a milestone branch for merging in all features
we want to add to XCM, roughly outlined
[here](https://github.com/polkadot-fellows/xcm-format/issues/60).
More features could be added.

## TODO
- [x] Migrate foreign assets from v3 to v4
- [x] Setup v5 skeleton
- [x] Remove XCMv2
- [x] https://github.com/paritytech/polkadot-sdk/pull/5390
- [x] https://github.com/paritytech/polkadot-sdk/pull/5585
- [x] https://github.com/paritytech/polkadot-sdk/pull/5420
- [x] https://github.com/paritytech/polkadot-sdk/pull/5876
- [x] https://github.com/paritytech/polkadot-sdk/pull/5971
- [x] https://github.com/paritytech/polkadot-sdk/pull/6148
- [x] https://github.com/paritytech/polkadot-sdk/pull/6228

Fixes #3434 
Fixes https://github.com/paritytech/polkadot-sdk/issues/4190
Fixes https://github.com/paritytech/polkadot-sdk/issues/5209
Fixes https://github.com/paritytech/polkadot-sdk/issues/5241
Fixes https://github.com/paritytech/polkadot-sdk/issues/4284

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Signed-off-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Andrii <ndk@parity.io>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: Joseph Zhao <65984904+programskillforverification@users.noreply.github.com>
Co-authored-by: Nazar Mokrynskyi <nazar@mokrynskyi.com>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Serban Iorga <serban@parity.io>

# Context

XCM docs are currently an md book hosted with github pages:
https://paritytech.github.io/xcm-docs/.
While that's fine, it's not in line with the work being done in the
polkadot-sdk docs.

# Main addition

This PR aims to fix that by bringing the docs back to this repo.
This does not have all the information currently present in the mdbook
xcm-docs but aims to be a good chunk of it and fully replace it over
time.

I also added the sections `guides` and `cookbook` which will be very
useful for users wanting to get into XCM.
For now I only added one example to the cookbook, but have ideas for
guides and more examples.
Having this docs be in rust docs is very useful for the cookbook.

# TODO

- [x] Use `FungibleAdapter`
- [x] Improve and relocate mock message queue
- [x] Fix license issue. Why does docs/sdk/ not have this problem? (Just
added the licenses)

# Next steps

- More examples in the cookbook
- End-to-end XCM guide with zombienet testing

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Co-authored-by: command-bot <>
Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>

This PR does a "developer experience" refactor of the XCM Simulator
Example.

I was looking for existing code / documentation where developers could
better learn about working with and configuring XCM.

The XCM Simulator was a natural starting point due to the fact that it
can emulate end to end XCM scenarios, without needing to spawn multiple
real chains.

However, the XCM Simulator Example was just 3 giant files with a ton of
configurations, runtime, pallets, and tests mashed together.

This PR breaks down the XCM Simulator Example in a way that I believe is
more approachable by a new developer who is looking to navigate the
various components of the end to end example, and modify it themselves.

The basic structure is:

- xcm simulator example
    - lib (tries to only use the xcm simulator macros)
    - tests
    - relay-chain
        - mod (basic runtime that developers should be familiar with)
        - xcm-config
            - mod (contains the `XcmConfig` type
            - various files for each custom configuration  
    - parachain
        - mock_msg_queue (custom pallet for simulator example)
        - mod (basic runtime that developers should be familiar with)
        - xcm-config
            - mod (contains the `XcmConfig` type
            - various files for each custom configuration

I would like to add more documentation to this too, but I think this is
a first step to be accepted which will affect how documentation is added
to the example

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Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>