Liquidity Pool

A Uniswap V2-style AMM liquidity pool implemented in Solidity, tested with the Ape Framework.

Contracts

LiquidityPool.sol

A constant-product AMM (x * y = k) with:

• addLiquidity(uint amount0, uint amount1) — deposit tokens, receive LP tokens (geometric mean on first deposit, proportional thereafter)
• removeLiquidity(uint liquidity) — burn LP tokens, receive proportional share of reserves
• swap(uint amount0Out, uint amount1Out) — swap with 0.3% fee, enforces the K invariant
• getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) — quote output amount for a given input
• getReserves() — returns current (reserve0, reserve1)

MockERC20.sol

Minimal ERC-20 used in tests. Supports mint, transfer, transferFrom, and approve.

Project Structure

contracts/
  lp.sol              # LiquidityPool contract
  MockERC20.sol       # Test token
tests/
  test_lp.py          # 23 tests for LiquidityPool
  test_mock_erc20.py  # 26 tests for MockERC20
ape-config.yaml       # Ape project config (pinned solc 0.8.20)

Setup

Requirements: Python 3.13+

uv sync

Commands

Compile

ape compile                        # compile all contracts
ape compile --force                # recompile even if unchanged

Test

ape test                           # run all tests
ape test -v                        # verbose output
ape test -s                        # show print statements
ape test tests/test_lp.py          # LP tests only
ape test tests/test_mock_erc20.py  # ERC-20 tests only
ape test -k test_swap              # run tests matching a keyword

Console (interactive)

ape console --network ethereum:local:foundry

License

This project is licensed under the MIT License. See the LICENSE file for details.