Complete Lending Protocol

Key takeaway: This final section verifies the complete Compound V2 protocol with cToken, Comptroller, PriceOracle, JumpRateModel, and CErc20 wrappers all integrated and passing the full 207-test suite. By this point you have a deployable lending protocol you understand line-by-line, including the parts that audit firms typically charge $50K to $150K to review. Run the deploy scripts and you have your own Compound V2 fork without the inherited bug surface most forks ship with.

What You Built

You just wrote a complete lending protocol. Not a simplified tutorial version. The actual architecture that powered Compound V2, held over $10 billion in deposits, and was forked by Aave V2, Venus, Benqi, Cream, Iron Bank, and dozens of others. Every function you implemented has a direct counterpart in the deployed Compound V2 contracts on Ethereum mainnet.

Here is the full inheritance chain you built, from bottom to top:

ExponentialNoError (fixed-point math)
  -> CTokenStorage (state variables, events, interfaces)
    -> CTokenInterest (accrueInterest, exchangeRate, borrowBalance)
      -> CTokenMint (supply underlying, receive cTokens)
        -> CTokenRedeem (burn cTokens, withdraw underlying)
          -> CTokenBorrow (take out loans against collateral)
            -> CTokenRepay (return borrowed tokens, reduce debt)
              -> CTokenLiquidate (seize collateral from underwater positions)
                -> CErc20 (public entry points, ERC-20 transfers, initialization)

And the risk engine:

ExponentialNoError
  -> ComptrollerMarkets (market registry, enter/exit markets)
    -> ComptrollerLiquidity (cross-market solvency calculation)
      -> ComptrollerHooks (policy enforcement: mint/redeem/borrow/repay/liquidate/seize/transfer)