[Testing] Design and implement PATH integration tests

[adshmh]

Objective

Design and implement integration tests for PATH components, more specifically for QoS and Protocol.

Origin Document

Integration tests are required to verify correct behavior in a fine-grained manner on critical components like QoS and Protocol.

The existing E2E test suite is very useful for verifying overall correct operation. However, it cannot verify the behavior at the desired granularity level for some of the components, e.g. we need to verify that qos/solana implementation correctly filters out all bad endpoints for which it has received observations.

Goals

• Improve development speed by running integration tests locally and on CI.
• Minimize the risk of breaking correct but hard-to-measure behavior, specifically in different service implementations under the qos package.

Deliverables

• [ ] Integration tests covering Solana QoS (qos/solana)
• [ ] Integration tests covering EVM QoS (qos/evm)
• [ ] Integration tests covering Shannon Protocol (protocol/shannon)
• [ ] Any required documentation for running the integration tests (ideally should need a simple build tag)
• [ ] Prefer consistency with poktroll repo integration tests style (e.g. use gomock).

Non-goals / Non-deliverables

• Integration tests covering the entire code base (more of a long-term goal)

General deliverables

• [ ] Comments: Add/update TODOs and comments alongside the source code so it is easier to follow.
• [ ] Testing: Add new tests (unit and/or E2E) to the test suite.
• [ ] Makefile: Add new targets to the Makefile to make the new functionality easier to use.
• [ ] Documentation: Update architectural or development READMEs; use mermaid diagrams where appropriate.

Creator: [@adshmh ]

[Olshansk]

@adshmh Please prepare a lightweight design doc on notion before tackling this so we can align on the direction this will take.