Stylus Test Helpers

Testing in Stylus is limited today. While developing OpenZeppelin Contracts for Stylus we created a few helpers to test our contracts, and we've decided to open source them and publish them as a separate crate for the community, at least until a more comprehensive testing framework is available.

This crate is a work in progress, and we'll be adding more features and improving the ergonomics as we go. We encourage projects that find this useful to contribute by opening issues and pull requests.

Motsu (持つ) - Unit Testing for Stylus

This crate enables unit-testing for Stylus contracts. It abstracts away the machinery necessary for writing tests behind a #[motsu::test] procedural macro.

motsu means "to hold" in Japanese -- we hold a stylus in our hand.

Usage

You can import motsu from crates.io by adding the following line to your Cargo.toml:

[dev-dependencies]
motsu = "0.2.1"

Then, when writing tests, use #[motsu::test] instead of #[test] to get access to VM affordances.

Note that we require contracts to implement stylus_sdk::prelude::StorageType. This trait is typically implemented by default with stylus_proc::sol_storage or stylus_proc::storage macros.

#[cfg(test)]
mod tests {
    use contracts::token::erc20::Erc20;

    #[motsu::test]
    fn reads_balance(contract: Erc20) {
        let balance = contract.balance_of(Address::ZERO); // Access storage.
        assert_eq!(balance, U256::ZERO);
    }
}

Annotating a test function that accepts no parameters will make #[motsu::test] behave the same as #[test].

#[cfg(test)]
mod tests {
    #[motsu::test]
     fn t() { // If no params, it expands to a `#[test]`.
        // ...
    }
}

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