Testing

Thanks to the Odra framework, you can test your code in any way you are used to. This means you can write regular Rust unit and integration tests. Have a look at how we test the Dog Contract we created in the previous article:

examples/src/features/storage/list.rs

use odra::{Variable, List};

#[cfg(test)]
mod tests {
    use super::DogContract3Deployer;

    #[test]
    fn init_test() {
        let mut dog_contract = DogContract3Deployer::init("Mantus".to_string());
        assert_eq!(dog_contract.walks_amount(), 0);
        assert_eq!(dog_contract.walks_total_length(), 0);
        dog_contract.walk_the_dog(5);
        dog_contract.walk_the_dog(10);
        assert_eq!(dog_contract.walks_amount(), 2);
        assert_eq!(dog_contract.walks_total_length(), 15);
    }
}

The #[odra(module)] macro created a Deployer code for us, which will deploy the contract on the VM:

examples/src/features/storage/list.rs

let mut dog_contract = DogContract3Deployer::init("Mantus".to_string());

From now on, we can use dog_contract to interact with our deployed contract - in particular, all pub functions from the impl section that was annotated with a macro are available to us:

examples/src/features/storage/list.rs

// Impl
pub fn walk_the_dog(&mut self, length: u32) {
    self.walks.push(length);
}

...

// Test
dog_contract.walk_the_dog(5);

Test env

Odra gives us some additional functions that we can use to communicate with the host (outside the contract context) and to configure how the contracts are deployed and called. Let's revisit the example from the previous article about host communication and implement the tests that prove it works:

examples/src/features/testing.rs

#[cfg(test)]
mod tests {
    use super::TestingContractDeployer;

    #[test]
    fn test_env() {
        let testing_contract = TestingContractDeployer::init("MyContract".to_string());
        let creator = testing_contract.created_by();
        odra::test_env::set_caller(odra::test_env::get_account(1));
        let testing_contract2 = TestingContractDeployer::init("MyContract2".to_string());
        let creator2 = testing_contract2.created_by();
        assert!(creator != creator2);
    }
}

In the code above, we are deploying two instances of the same contract, but we're using odra::test_env::set_caller to change the caller - so the Address which is deploying the contract. This changes the result of the odra::contract_env::caller() the function we are calling inside the contract.

Each test env comes with a set of functions that will let you write better tests:

• fn set_caller(address: Address) - you've seen it in action just now
• fn token_balance(address: Address) -> Balance - it returns the balance of the account associated with the given address
• fn advance_block_time_by(seconds: BlockTime) - it increases the current value of block_time
• fn get_account(n: usize) -> Address - it returns an nth address that was prepared for you by Odra in advance; by default, you start with the 0th account
• fn assert_exception<F, E>(err: E, block: F) - it executes the block code and expects err to happen
• fn get_event<T: MockVMType + OdraEvent>(address: Address, index: i32) -> Result<T, EventError> - returns the event emitted by the contract

Again, we'll see those used in the next articles.

Deployer

You may be wondering what is the TestingContractDeployer and where did it come from. It is a piece of code generated automatically for you, thanks to the #[odra::module] macro. If you used the #[odra(init)] on one of the methods, it will be the constructor of your contract. Odra will make sure that it is called only once, so you can use it to initialize your data structures etc.

If you do not provide the init method, you can deploy the contract using ::default() method. In the end, you will get a Ref instance (in our case the TestingContractRef) which reimplements all the methods you defined in the contract, but executes them on a blockchain!

To learn more about the Ref contract, visit the Cross calls article.

What's next

We take a look at how Odra handles errors!