Simple SDK for simulating the exact on-chain behaviour of various Balancer v2 pools.
The SDK tries to be as lean as possible in order to prioritize certain critical usages (such as Balancer's SOR). For this reason, it only provides the bare-minimum for simulating Balancer pools off-chain. However, higher-level constructs (like initializing pools directly from on-chain data or the official Balancer subgraph) are still available. In order to be able to use these, make sure to install any peer dependencies of this package (eg. via npm-install-peers).
import { JsonRpcProvider } from "@ethersproject/providers";
import { WeightedPool } from "@georgeroman/balancer-v2-pools";
import { initFromOnchain } from "@georgeroman/balancer-v2-pools/dist/src/initializers/weighted";
const provider = new JsonRpcProvider(process.env.RPC_ENDPOINT);
// WETH/DAI 60/40 on Mainnet
const pool = await initFromOnchain(
provider,
"0x0b09dea16768f0799065c475be02919503cb2a3500020000000000000000001a",
"mainnet"
);
// Swap
const amountOut = pool.swapGivenIn("WETH", "DAI", "100");
// Join
const bptOut = pool.joinExactTokensInForBptOut({
WETH: "1",
DAI: "2000",
});
// Exit
const tokensOut = pool.exitExactBptInForTokensOut("1.23");Mainnet forking is used for testing in order to make sure the SDK exactly match the EVM. Make sure to have a .env file in the root directory, containing the following definitions (the given block number must include the instances of the pools used in the tests):
RPC_URL=
BLOCK_NUMBER=The setup I recommend for deterministic tests is the following:
RPC_URL=https://eth-mainnet.alchemyapi.io/v2/${ALCHEMY_KEY}
BLOCK_NUMBER=13128465To execute the tests locally, simply run:
# Install dependencies
npm install
# Run tests
npm test