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Using Chainlink Data Feeds with BuildBear Sandbox

Learn how to test Chainlink Data Feeds with UniLend and Aave protocols using BuildBear's Sandbox environment.

Introduction

This guide walks through how to integrate and test Chainlink Price Feeds using BuildBear’s Sandbox environment. We'll explore two real-world examples:

  1. Integrating Chainlink Price Feeds with UniLend's BorrowSwap contract
  2. Testing Aave interactions using live Chainlink data with DeFi Saver

BuildBear’s private Testnets offer the perfect environment to simulate real-time conditions with minimal setup.

  • Mainnet Forking – Access existing Chainlink contracts deployed on Ethereum
  • Rapid Transactions – < 3s confirmation for faster testing
  • Unlimited Token Minting – Get any ERC20 or native token via Faucet
  • Private Explorer – Debug and verify transactions
  • Plugin Support – Enable Chainlink Feeds without complex mocks

UniLend BorrowSwap Integration

Step 1: Setup BuildBear

  1. Create a BuildBear account.
  2. Fork Ethereum Mainnet.
  3. Navigate to Plugin Marketplace.
  4. Enable Chainlink Data Feed Plugin.
  5. Choose a price feed (e.g., ETH/USD).
  6. Launch the plugin dashboard to manage feeds.

Step 2: Clone and Configure Project

git clone https://github.com/UniLend/borrowswap-contracts.git
cd borrowswap-contracts
npm install

The Oracle contract imports Chainlink’s AggregatorInterface to fetch live price data for assets. The interface allows your contract to query the latest price data, round information, and timestamps directly from Chainlink oracles. Deploy the Oracle contract using the following in the deployment script:

const oracle = await ethers.deployContract('PriceFeed');
await oracle.waitForDeployment();
console.log('Oracle contract deployed at:', oracle.target);
 
const priceFeedAddress = "0xF9680D99D6C9589e2a93a78A04A279e509205945";
const latestPrice = await oracle.getLatestPrice(priceFeedAddress);
console.log(`Latest price: ${latestPrice}`);

Run using Hardhat:

npx hardhat run scripts/deploy.ts --network buildbear

🔎 Find Chainlink addresses on the Chainlink Docs page.

Aave Integration with DeFi Saver

  • Fork Ethereum Mainnet in BuildBear.
  • Enable the Chainlink Price Feed Plugin.
  • Select a data feed (e.g., ETH/USD).

Step 2: Setup DeFi Saver Contracts

git clone https://github.com/defisaver/defisaver-v3-contracts.git
cd defisaver-v3-contracts
npm install

Step 3: Configure BuildBear RPC

buildbear: {
  url: 'https://rpc.dev.buildbear.io/sanam',
  timeout: 1000000,
  name: 'mainnet',
  chainId: 1,
},

Step 4: Deploy and Test

npm run deploy buildbear deploy-on-fork

DeFi Saver’s AaveV3QuotePriceTrigger checks token price thresholds using Chainlink feeds and triggers Aave actions (e.g., refinancing, liquidation). With BuildBear, you test the entire flow using real Chainlink feeds, not mocks.

Conclusion

BuildBear provides a highly realistic and configurable test environment to validate smart contracts integrating Chainlink Data Feeds. Whether testing lending/borrowing on Aave or swapping with UniLend, developers can now simulate mainnet behavior confidently and cost-effectively.

Use BuildBear to:

  • Avoid mock contracts
  • Fetch live prices via Chainlink
  • Validate workflows before mainnet deploys
  • Speed up testing cycles with mainnet forks