README.md

EvmPriceFeed

Implements a simple price feed with EVM Offchain Rollup. It supports streaming a price feed and answering individual requests from the EVM side.

Run a full unit tests

To run the unit tests:

cargo test

The contract logs to env_logger. To run with logger enabled:

RUST_LOG=info RUST_BACKTRACE=1 cargo test -- --nocapture

Some tests involving EVM testnet setup are marked as ignored. To run the full tests:

1. Start a local hardhat testnet and deploy the EVM

   cd evm
   # Run `yarn` to init the repo if you haven't done it before
   # Run the two command below in separate windows / panes
   npx hardhat node
   npx hardhat run --network localhost ./scripts/deploy-test.ts

2. Copy .env_sample as .env if you haven't done it before. It tells the Phat Contract to connect to the local EVM testnet you just created.

3. Run the full e2e test:

   cargo test -- --ignored --test-threads=1

Parallel in Unit Tests

The flag --test-threads=1 is necessary because by default Rust unit tests run in parallel. There may have a few tests trying to sending out transactions at the same time, resulting conflicting nonce values. In such case, you will get EVM erros like below:

RpcError { code: -32000, message: \"Nonce too low. Expected nonce to be 8 but got 7.\" }

The solution is to add --test-threads=1. So the unit test framework knows that you don't want parallel execution.

Push More Requests

After running deploy-test.ts, it will push only one oracle reqeust to the rollup queue. After a successful answer_price_request test run, the queue will become empty. To push a new request, run:

npx hardhat run --network localhost ./scripts/testnet-push-request.ts

Enable Meta-Tx

Meta transaction allows the Phat Contract to submit rollup tx with attest key signature while using arbitrary account to pay the gas fee. To enable meta tx in the unit test, change the .env file and specify SENDER_KEY.