Summary of Changes

Hello @LucaCappelletti94, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces comprehensive support for fuzz testing by integrating the arbitrary crate. It allows for the generation of random, well-formed PostgreSQL logical replication messages and associated data structures, which is crucial for robust testing and discovering edge cases in protocol handling. The changes are encapsulated within an optional feature, maintaining a lean dependency tree for standard builds.

Highlights

• Fuzzing Support: Added the arbitrary crate as an optional dependency to enable fuzzing capabilities for data structures representing PostgreSQL logical replication protocols.
• Arbitrary Trait Implementations: Implemented the arbitrary::Arbitrary trait for key protocol-related enums and structs, including MessageType, LogicalReplicationMessage, ColumnData, CachePadded, and ReplicaIdentity, allowing them to be randomly generated for testing.
• Conditional Compilation: All arbitrary implementations and dependencies are guarded by a new arbitrary feature, ensuring that the fuzzing-specific code is only compiled when explicitly enabled.

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Codecov Report

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Hi @LucaCappelletti94 thank you for your PR, I didn't use arbitrary crate lib before, as I reviewed from https://github.com/rust-fuzz/arbitrary github readme and docs https://docs.rs/arbitrary/latest/arbitrary/, as my understanding it's generally intended to be used with random fuzzers structured.

however, could you share more detail or used case that benefit for this lib that we really need that? so far, I haven't come up with any scenario where it would be necessary to provide a fuzzing API to the client.

Basically, I wrote a crate for the SQLite patchset format, which I directly attach on top of a logical stream. My crate needs to be solid and able to handle any possible input of your crate without crashing, hence the fuzzer.

Specifically, I use honggfuzz.

Hi @LucaCappelletti94 can we use arbitrary combine pg-walstream crate instead of modified that internally? because I don't want to introduce any code which don't relate to PostgreSQL replication protocol implement in this lib.

here is the example for Arbitrary for fuzzing #19

In my uses cases, I found that the simplest possible solution was:

• https://github.com/LucaCappelletti94/sqlite-diff-rs/blob/main/fuzz/fuzz_targets/pg_walstream.rs
• https://github.com/LucaCappelletti94/sqlite-diff-rs/blob/946fe20ce0181765338dedeae76fba7167ec53b7/src/testing.rs#L1012-L1026

Of course, this causes a MASSIVE amount of tests to be discarded, and that is what the structured Arbitrary impl should avoid.

I will study a bit more in details the proposed impl and review it asap.