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::{List, Var};

#[cfg(test)]
mod tests {
    use super::{DogContract3, DogContract3InitArgs};
    use odra::{host::Deployer, prelude::*};

    #[test]
    fn init_test() {
        let test_env = odra_test::env();
        let init_args = DogContract3InitArgs {
            name: "DogContract".to_string()
        };
        let mut dog_contract = DogContract3::deploy(&test_env, init_args);
        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 first interesting thing you may notice is placed the import section.

use super::{DogContract3, DogContract3InitArgs};
use odra::{host::Deployer, prelude::*};

We are using super to import the DogContract3 and DogContract3InitArgs from the parent module. {{ModuleName}}InitArgs is a type that was generated for us by Odra, alongside with the code in the code inside {{ModuleName}}.

DogContract3InitArgs is a struct that we use to initialize the contract and implements InitArgs trait. Considering the contract initialization, there three possible scenarios:

1. The contract has a constructor with arguments, then Odra creates a struct named {{ModuleName}}InitArgs.
2. The contract has a constructor with no arguments, then you can use odra::host::NoArgs.
3. The contract does not have a constructor, then you can use odra::host::NoArgs. All of those structs implement the odra::host::InitArgs trait, required to conform to the Deployer::deploy method signature.

The other import is odra::host::Deployer. This is a trait is used to deploy the contract and give us a reference to it.

Let's take a look at the test itself. How to obtain a reference to the contract? {{ModuleName}} implements the Deployer trait, which provides the deploy method:

examples/src/features/storage/list.rs

let mut dog_contract = DogContract3::deploy(&test_env, init_args);

From now on, we can use dog_contract to interact with our deployed contract. Its type is DogContract3HostRef, which is a reference to the contract that we can use to interact with it (call entrypoints) and implements HostRef trait. In particular, all pub functions from the impl section that was annotated with the odra::module attribute are available to us in this type:

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);

HostEnv

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 crate::features::testing::{TestingContract, TestingContractInitArgs};
    use odra::{host::{Deployer, HostEnv}, prelude::*};

    #[test]
    fn env() {
        let test_env: HostEnv = odra_test::env();
        test_env.set_caller(test_env.get_account(0));
        let init_args = TestingContractInitArgs {
            name: "MyContract".to_string()
        };
        let testing_contract = TestingContract::deploy(&test_env, init_args);
        let creator = testing_contract.created_by();
        test_env.set_caller(test_env.get_account(1));
        let init_args = TestingContractInitArgs {
            name: "MyContract2".to_string()
        };
        let testing_contract2 = TestingContract::deploy(&test_env, init_args);
        let creator2 = testing_contract2.created_by();
        assert_ne!(creator, creator2);
    }
}

In the code above, at the beginning of the test, we are obtaining a HostEnv instance using odra_test::env(). Next, we are deploying two instances of the same contract, but we're using HostEnv::set_caller to change the caller - so the Address which is deploying the contract. This changes the result of the odra::ContractEnv::caller() the function we are calling inside the contract.

HostEnv comes with a set of functions that will let you write better tests:

• fn set_caller(&self, address: Address) - you've seen it in action just now
• fn balance_of(&self, address: &Address) -> U512 - returns the balance of the account associated with the given address
• fn advance_block_time(&self, time_diff: u64) - increases the current value of block_time
• fn get_account(&self, n: usize) -> Address - returns an n-th address that was prepared for you by Odra in advance; by default, you start with the 0-th account
• fn emitted_event<T: ToBytes + EventInstance, R: Addressable>(&self, contract_address: &R, event: &T) -> bool - verifies if the event was emitted by the contract

Full list of functions can be found in the HostEnv documentation.

What's next

We take a look at how Odra handles errors!