I build a simple rust state machine, following the tutorial: "https://www.shawntabrizi.com/rust-state-machine/"

Overview

This project is a simple blockchain-style state machine written in Rust. It follows the tutorial from Shawn Tabrizi and includes a minimal runtime with:

• system pallet: block numbers and account nonces
• balances pallet: transfers between accounts
• proof_of_existence pallet: create and revoke ownership claims

Project Structure

• src/main.rs: runtime wiring and block execution examples
• src/system.rs: system-level state
• src/balances.rs: balances and transfer logic
• src/proof_of_existence.rs: claim and revoke logic
• src/support.rs: shared types (Block, Header, Extrinsic, Dispatch)

Requirements

• Rust (stable)
• Cargo

Run

cargo run

Test

Run all tests:

cargo test

Run tests by module:

cargo test --lib system::test:: -- --nocapture
cargo test --lib balances::tests:: -- --nocapture
cargo test --lib proof_of_existence::test:: -- --nocapture

Notes

• You can intentionally add invalid extrinsics in main.rs to demonstrate runtime error handling.

• The tutorial uses BTreeMap instead of HashMap to keep state deterministic (sorted keys) and trait bounds simple (Ord).

• The macros crate comes from the tutorial; I did not implement those macros myself.

• I added src/lib.rs so module tests can be run as library tests (for example, cargo test --lib system::test::).

• We could add transaction fees (gas) by deducting a small amount from the caller for each extrinsic execution (and other blockchain features), but this tutorial does not implement fees (Nobody likes fees).

• Why can cargo run show Extrinsic Error but still finish successfully? In this project, an extrinsic failure is logged, but block execution continues. In src/main.rs:62, each dispatch result is captured as _res and errors are only printed via map_err(...). The block still returns Ok(()) after processing extrinsics (unless the block number check fails in src/main.rs:54). This is because we do not want to panic and stop the blockchain because one extrinsic fails