Nova gives your L2 contracts the power to read and write to L1 with minimal latency and no trust tradeoffs.

• Documentation
• Whitepaper
• Audits

Architecture

• L1_NovaExecutionManager.sol: Entry point for relayers to execute requests.
• L2_NovaRegistry.sol: Hub for contracts/users on L2 to create and manage requests.
• L1_NovaApprovalEscrow.sol: Escrow contract for relayers to approve input tokens to.
• libraries/: Utilities used to help implement the Nova protocol.
  • SafeTransferLib.sol: Library for safely transferring Ether.
  • NovaExecHashLib.sol: Library for computing a Nova execHash.
• external/: Contracts and interfaces modified from external codebases.
  • CrossDomainEnabled.sol: Cross-domain communication helper mixin.

Testing

Below is a list of scripts used to test, fuzz, and measure the gas consumption of the Nova smart contracts. Many of these scripts are run automatically as part of our continuous integration suite.

Running Unit Tests

To fail tests when their gas snapshots are incorrect (default is only a warning), set the CI env var to true.

npm run unit-tests

Running Integration Tests

You must start up an instance of Optimism's "ops" repo before running integration tests.

npm run integration-tests

Updating Gas Snapshots

If you make a contribution that changes the gas usage of the contracts, you must run this command before committing.

npm run gas-changed

Running Unit Tests With Coverage

After running tests with coverage, an lcov report will be exported to coverage/index.html.

npm run coverage

Running Integration Tests On Kovan

You must set the PRIVATE_KEY and KOVAN_RPC_URL environment variables before running integration tests on Kovan.

npm run kovan-integration-tests

Fuzzing With Echidna

You must install Echidna before fuzzing.

npm run fuzz deep {{CONTRACT_NAME}}

Replace {{CONTRACT_NAME}} with a contract that is fuzzed in contracts/echidna. A full list can be found here:

https://github.com/Rari-Capital/nova/blob/master/.github/workflows/fuzz.yml#L13-L14

There are 3 fuzz "modes" setup for this project:

• deep enters coverage guided inputs until it is halted manually.

  • It uses coverage guided fuzzing, which makes it quite slow.
  • It is the most comprehensive mode (if run for long enough).

• long enters random inputs for 5 hours before halting.

  • It does not use coverage guided fuzzing.
  • Is less comprehensive than deep.

• quick enters random inputs for 20 minutes before halting.

  • It does not use coverage guided fuzzing.
  • Is less comprehensive than long.

To use any of these modes simply run the command above but replace deep with the mode you wish to use (long,quick, or deep).