Smart Contract Integration Tests

This tutorial covers testing smart contracts in realistic blockchain environments using cw-multi-test and full chain integration tests.

Prerequisites

Completed Chain Integration Tests
Understanding of CosmWasm contract development
Familiarity with Rust testing frameworks

Testing Approaches

1. Unit Tests

Test individual contract functions in isolation

2. Multi-Test Integration

Use cw-multi-test to simulate blockchain environment

3. Full Chain Integration

Test contracts on actual Neutron testnet or local chain

Setting Up Multi-Test Environment

1. Add Dependencies

Update your Cargo.toml:

[dev-dependencies]
cw-multi-test = "0.16"
cosmwasm-std = { version = "1.0", features = ["testing"] }
neutron-sdk = { version = "0.8", features = ["testing"] }

2. Basic Multi-Test Setup

Create src/multitest.rs:

use cosmwasm_std::{Addr, Coin, Decimal, Uint128};
use cw_multi_test::{App, ContractWrapper, Executor};
use neutron_sdk::bindings::{msg::NeutronMsg, query::NeutronQuery};

use crate::contract::{execute, instantiate, query};
use crate::msg::{ExecuteMsg, InstantiateMsg, QueryMsg};

pub struct TestEnv {
    pub app: App,
    pub owner: Addr,
    pub user: Addr,
    pub contract_addr: Addr,
}

impl TestEnv {
    pub fn new() -> Self {
        let mut app = App::default();
        
        let owner = Addr::unchecked("owner");
        let user = Addr::unchecked("user");
        
        // Give accounts some initial balances
        app.init_modules(|router, _, storage| {
            router
                .bank
                .init_balance(storage, &owner, vec![Coin::new(1000000, "untrn")])
                .unwrap();
            router
                .bank
                .init_balance(storage, &user, vec![Coin::new(1000000, "untrn")])
                .unwrap();
        });
        
        // Store and instantiate contract
        let contract_wrapper = ContractWrapper::new(execute, instantiate, query);
        let code_id = app.store_code(contract_wrapper);
        
        let contract_addr = app
            .instantiate_contract(
                code_id,
                owner.clone(),
                &InstantiateMsg {
                    initial_count: Uint128::zero(),
                    price_threshold: Decimal::from_str("10.0").unwrap(),
                    oracle_base: "ATOM".to_string(),
                    oracle_quote: "USD".to_string(),
                },
                &[],
                "test-contract",
                None,
            )
            .unwrap();
        
        Self {
            app,
            owner,
            user,
            contract_addr,
        }
    }
    
    pub fn increment(&mut self, sender: &Addr, amount: u128) -> anyhow::Result<()> {
        self.app.execute_contract(
            sender.clone(),
            self.contract_addr.clone(),
            &ExecuteMsg::Increment {
                amount: Uint128::new(amount),
            },
            &[],
        )?;
        Ok(())
    }
    
    pub fn query_count(&self) -> u128 {
        let resp: crate::msg::CountResponse = self
            .app
            .wrap()
            .query_wasm_smart(&self.contract_addr, &QueryMsg::GetCount {})
            .unwrap();
        resp.count.u128()
    }
}

Contract Testing Patterns

1. Basic Contract Tests

#[cfg(test)]
mod tests {
    use super::*;
    use cosmwasm_std::testing::{mock_dependencies, mock_env, mock_info};
    
    #[test]
    fn test_instantiate() {
        let mut deps = mock_dependencies();
        let env = mock_env();
        let info = mock_info("creator", &[]);
        
        let msg = InstantiateMsg {
            initial_count: Uint128::zero(),
            price_threshold: Decimal::from_str("10.0").unwrap(),
            oracle_base: "ATOM".to_string(),
            oracle_quote: "USD".to_string(),
        };
        
        let res = instantiate(deps.as_mut(), env, info, msg).unwrap();
        assert_eq!(res.attributes.len(), 2);
    }
    
    #[test]
    fn test_increment() {
        let mut deps = mock_dependencies();
        let env = mock_env();
        let info = mock_info("anyone", &[]);
        
        // Instantiate first
        let instantiate_msg = InstantiateMsg {
            initial_count: Uint128::zero(),
            price_threshold: Decimal::from_str("10.0").unwrap(),
            oracle_base: "ATOM".to_string(),
            oracle_quote: "USD".to_string(),
        };
        instantiate(deps.as_mut(), env.clone(), info.clone(), instantiate_msg).unwrap();
        
        // Test increment
        let execute_msg = ExecuteMsg::Increment {
            amount: Uint128::new(5),
        };
        let res = execute(deps.as_mut(), env.clone(), info, execute_msg).unwrap();
        
        // Verify response
        assert_eq!(res.attributes.len(), 3);
        assert_eq!(res.attributes[1].value, "5");
        
        // Query the new count
        let query_msg = QueryMsg::GetCount {};
        let res = query(deps.as_ref(), env, query_msg).unwrap();
        let count_response: CountResponse = from_binary(&res).unwrap();
        assert_eq!(count_response.count, Uint128::new(5));
    }
    
    #[test]
    fn test_increment_exceeds_limit() {
        let mut deps = mock_dependencies();
        let env = mock_env();
        let info = mock_info("anyone", &[]);
        
        // Instantiate first
        let instantiate_msg = InstantiateMsg {
            initial_count: Uint128::zero(),
            price_threshold: Decimal::from_str("10.0").unwrap(),
            oracle_base: "ATOM".to_string(),
            oracle_quote: "USD".to_string(),
        };
        instantiate(deps.as_mut(), env.clone(), info.clone(), instantiate_msg).unwrap();
        
        // Test increment that exceeds limit
        let execute_msg = ExecuteMsg::Increment {
            amount: Uint128::new(150), // Exceeds limit of 100
        };
        let err = execute(deps.as_mut(), env, info, execute_msg).unwrap_err();
        assert!(err.to_string().contains("Cannot increment by more than 100"));
    }
}

2. Multi-Test Integration Tests

#[cfg(test)]
mod multitest {
    use super::*;
    
    #[test]
    fn test_multitest_basic_flow() {
        let mut env = TestEnv::new();
        
        // Initial count should be 0
        assert_eq!(env.query_count(), 0);
        
        // Increment by 5
        env.increment(&env.user, 5).unwrap();
        assert_eq!(env.query_count(), 5);
        
        // Increment by another 10
        env.increment(&env.user, 10).unwrap();
        assert_eq!(env.query_count(), 15);
    }
    
    #[test]
    fn test_multitest_multiple_users() {
        let mut env = TestEnv::new();
        
        let user2 = Addr::unchecked("user2");
        
        // Give user2 some tokens
        env.app.init_modules(|router, _, storage| {
            router
                .bank
                .init_balance(storage, &user2, vec![Coin::new(1000000, "untrn")])
                .unwrap();
        });
        
        // Both users increment
        env.increment(&env.user, 3).unwrap();
        env.increment(&user2, 7).unwrap();
        
        assert_eq!(env.query_count(), 10);
    }
    
    #[test]
    fn test_multitest_with_funds() {
        let mut env = TestEnv::new();
        
        // Test contract execution with funds
        let funds = vec![Coin::new(100, "untrn")];
        
        let res = env.app.execute_contract(
            env.user.clone(),
            env.contract_addr.clone(),
            &ExecuteMsg::Increment {
                amount: Uint128::new(1),
            },
            &funds,
        );
        
        assert!(res.is_ok());
        assert_eq!(env.query_count(), 1);
    }
}

3. Neutron Module Integration

Test contracts that interact with Neutron modules:

use neutron_sdk::bindings::{
    msg::NeutronMsg,
    query::NeutronQuery,
    types::{Height, InterchainQueryResult},
};

// Mock Neutron query responses
pub fn mock_neutron_dependencies() -> OwnedDeps<MockStorage, MockApi, NeutronMockQuerier> {
    let custom_querier = NeutronMockQuerier::new(MockQuerier::new(&[]));
    OwnedDeps {
        storage: MockStorage::default(),
        api: MockApi::default(),
        querier: custom_querier,
        custom_query_type: PhantomData,
    }
}

pub struct NeutronMockQuerier {
    base: MockQuerier,
}

impl NeutronMockQuerier {
    pub fn new(base: MockQuerier) -> Self {
        NeutronMockQuerier { base }
    }
    
    pub fn with_oracle_price(&mut self, denom: &str, price: Decimal) {
        // Set up mock oracle price response
    }
}

impl Querier for NeutronMockQuerier {
    fn raw_query(&self, bin_request: &[u8]) -> QuerierResult {
        let request: QueryRequest<NeutronQuery> = match from_slice(bin_request) {
            Ok(v) => v,
            Err(e) => {
                return SystemResult::Err(SystemError::InvalidRequest {
                    error: format!("Parsing query request: {}", e),
                    request: bin_request.into(),
                });
            }
        };
        
        match &request {
            QueryRequest::Custom(NeutronQuery::Oracle { base, quote }) => {
                // Return mock oracle price
                let price = Decimal::from_str("15.0").unwrap();
                let response = OraclePriceResponse { price };
                SystemResult::Ok(ContractResult::Ok(to_binary(&response).unwrap()))
            }
            _ => self.base.handle_query(&request),
        }
    }
}

#[test]
fn test_oracle_integration() {
    let mut deps = mock_neutron_dependencies();
    deps.querier.with_oracle_price("ATOM/USD", Decimal::from_str("15.0").unwrap());
    
    let env = mock_env();
    let info = mock_info("user", &[]);
    
    // Test price-checked increment
    let msg = ExecuteMsg::CheckPriceAndIncrement {
        amount: Uint128::new(5),
    };
    
    let res = execute(deps.as_mut(), env, info, msg).unwrap();
    assert!(res.attributes.iter().any(|attr| attr.value == "5"));
}

Full Chain Integration Tests

1. Local Chain Testing

use std::process::Command;
use tempfile::TempDir;

pub struct LocalChain {
    pub chain_dir: TempDir,
    pub rpc_port: u16,
    pub grpc_port: u16,
}

impl LocalChain {
    pub fn new() -> Self {
        let chain_dir = TempDir::new().unwrap();
        let rpc_port = 26657;
        let grpc_port = 9090;
        
        // Initialize chain
        Command::new("neutrond")
            .args(&[
                "init",
                "test-node",
                "--chain-id",
                "neutron-testing-1",
                "--home",
                chain_dir.path().to_str().unwrap(),
            ])
            .output()
            .expect("Failed to initialize chain");
        
        // Add genesis account
        Command::new("neutrond")
            .args(&[
                "add-genesis-account",
                "neutron1...", // Test account address
                "1000000000untrn",
                "--home",
                chain_dir.path().to_str().unwrap(),
            ])
            .output()
            .expect("Failed to add genesis account");
        
        Self {
            chain_dir,
            rpc_port,
            grpc_port,
        }
    }
    
    pub fn start(&self) {
        Command::new("neutrond")
            .args(&[
                "start",
                "--home",
                self.chain_dir.path().to_str().unwrap(),
                "--rpc.laddr",
                &format!("tcp://0.0.0.0:{}", self.rpc_port),
                "--grpc.address",
                &format!("0.0.0.0:{}", self.grpc_port),
            ])
            .spawn()
            .expect("Failed to start chain");
    }
}

#[test]
fn test_full_chain_contract_deployment() {
    let chain = LocalChain::new();
    chain.start();
    
    // Wait for chain to be ready
    std::thread::sleep(std::time::Duration::from_secs(5));
    
    // Deploy contract using CLI
    let output = Command::new("neutrond")
        .args(&[
            "tx",
            "wasm",
            "store",
            "artifacts/contract.wasm",
            "--from",
            "test-key",
            "--chain-id",
            "neutron-testing-1",
            "--node",
            &format!("http://localhost:{}", chain.rpc_port),
            "--yes",
        ])
        .output()
        .expect("Failed to store contract");
    
    assert!(output.status.success());
}

2. End-to-End Testing

use cosmrs::{
    crypto::secp256k1::SigningKey,
    tx::{self, SignerInfo, Tx},
    AccountId, Coin,
};

#[tokio::test]
async fn test_e2e_contract_interaction() {
    let rpc_client = HttpClient::new("http://localhost:26657").unwrap();
    
    // Create signing key
    let signing_key = SigningKey::random(&mut rand::thread_rng());
    let account_id = AccountId::new("neutron", &signing_key.public_key()).unwrap();
    
    // Query account info
    let account = rpc_client
        .abci_query(
            Some("account".to_string()),
            account_id.to_bytes(),
            None,
            false,
        )
        .await
        .unwrap();
    
    // Build and sign transaction
    let msg = MsgExecuteContract {
        sender: account_id.to_string(),
        contract: "neutron1...".to_string(),
        msg: br#"{"increment":{"amount":"1"}}"#.to_vec(),
        funds: vec![],
    };
    
    let tx_body = tx::Body::new(vec![msg.to_any().unwrap()], "", 0u32);
    
    let signer_info = SignerInfo::single_direct(Some(signing_key.public_key()), 0);
    let auth_info = signer_info.auth_info(tx::Fee::from_amount_and_gas(
        Coin::new(5000u128, "untrn").unwrap(),
        200_000u64,
    ));
    
    let sign_doc = tx::SignDoc::new(&tx_body, &auth_info, "neutron-testing-1", 0u64).unwrap();
    let tx_signed = Tx::new(tx_body, auth_info, vec![signing_key.sign(&sign_doc).unwrap()]).unwrap();
    
    // Broadcast transaction
    let response = rpc_client.broadcast_tx_commit(tx_signed.to_bytes().unwrap()).await.unwrap();
    
    assert_eq!(response.check_tx.code, 0.into());
    assert_eq!(response.deliver_tx.code, 0.into());
}

Performance Testing

1. Gas Usage Analysis

#[test]
fn test_gas_usage() {
    let mut env = TestEnv::new();
    
    // Track gas usage for different operations
    let gas_before = env.app.block_info().gas_used;
    
    env.increment(&env.user, 1).unwrap();
    
    let gas_after = env.app.block_info().gas_used;
    let gas_used = gas_after - gas_before;
    
    // Assert gas usage is within expected range
    assert!(gas_used < 100_000, "Gas usage too high: {}", gas_used);
    assert!(gas_used > 30_000, "Gas usage suspiciously low: {}", gas_used);
}

2. Load Testing

#[test]
fn test_load_handling() {
    let mut env = TestEnv::new();
    
    // Execute many operations
    for i in 0..1000 {
        let user = Addr::unchecked(format!("user{}", i));
        env.increment(&user, 1).unwrap();
    }
    
    assert_eq!(env.query_count(), 1000);
}

CI/CD Integration

Create .github/workflows/contract-tests.yml:

name: Contract Tests

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  test:
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Install Rust
      uses: actions-rs/toolchain@v1
      with:
        toolchain: stable
        target: wasm32-unknown-unknown
        
    - name: Run unit tests
      run: cargo test --lib
      
    - name: Run integration tests
      run: cargo test --test integration
      
    - name: Build contract
      run: cargo wasm
      
    - name: Optimize contract
      run: |
        docker run --rm -v "$(pwd)":/code \
          --mount type=volume,source="$(basename "$(pwd)")_cache",target=/code/target \
          --mount type=volume,source=registry_cache,target=/usr/local/cargo/registry \
          cosmwasm/rust-optimizer:0.12.13

Best Practices

Test Pyramid: More unit tests, fewer integration tests, minimal E2E tests
Isolation: Each test should be independent
Fast Feedback: Unit tests should run quickly
Realistic Data: Use realistic test data and scenarios
Error Cases: Test both success and failure paths
Documentation: Document complex test setups

Troubleshooting

Multi-test Setup Issues

Ensure you’re using compatible versions of cw-multi-test and cosmwasm-std:

cw-multi-test = "0.16"
cosmwasm-std = "1.0"

Mock Querier Problems

Implement all required query handlers in your mock querier, or use default implementations.

Local Chain Won't Start

Check port availability and ensure neutrond binary is in PATH:

lsof -i :26657
which neutrond

Proper testing ensures your smart contracts work correctly and safely in production environments. Start with unit tests and gradually add integration tests for complex scenarios.

Getting Started

Tutorials

Modules

Prerequisites

Testing Approaches

1. Unit Tests

2. Multi-Test Integration

3. Full Chain Integration

Setting Up Multi-Test Environment

1. Add Dependencies

2. Basic Multi-Test Setup

Contract Testing Patterns

1. Basic Contract Tests

2. Multi-Test Integration Tests

3. Neutron Module Integration

Full Chain Integration Tests

1. Local Chain Testing

2. End-to-End Testing

Performance Testing

1. Gas Usage Analysis

2. Load Testing

CI/CD Integration

Best Practices

Troubleshooting

Getting Started

Tutorials

Modules

​Prerequisites

​Testing Approaches

​1. Unit Tests

​2. Multi-Test Integration

​3. Full Chain Integration

​Setting Up Multi-Test Environment

​1. Add Dependencies

​2. Basic Multi-Test Setup

​Contract Testing Patterns

​1. Basic Contract Tests

​2. Multi-Test Integration Tests

​3. Neutron Module Integration

​Full Chain Integration Tests

​1. Local Chain Testing

​2. End-to-End Testing

​Performance Testing

​1. Gas Usage Analysis

​2. Load Testing

​CI/CD Integration

​Best Practices

​Troubleshooting

Prerequisites

Testing Approaches

1. Unit Tests

2. Multi-Test Integration

3. Full Chain Integration

Setting Up Multi-Test Environment

1. Add Dependencies

2. Basic Multi-Test Setup

Contract Testing Patterns

1. Basic Contract Tests

2. Multi-Test Integration Tests

3. Neutron Module Integration

Full Chain Integration Tests

1. Local Chain Testing

2. End-to-End Testing

Performance Testing

1. Gas Usage Analysis

2. Load Testing

CI/CD Integration

Best Practices

Troubleshooting