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testingsoliditysmartcontractshardhat

Testing Token with Uniswap liquidity provisioning using hardhat

I'm attempting to fork Safemoon (or really NotSafeMoon), and use it as a vehicle to learn smart contract development. (I've got a substantial amount of what you might call "Web 2.0" dev experience).

So say I have something like so in my constructor:

constructor () {
        _rOwned[_msgSender()] = _rTotal;
        IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(0x10ED43C718714eb63d5aA57B78B54704E256024E);       // binance PANCAKE V2
        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _uniswapV2Router.WETH());

When I run my tests with npx hardhat test I get the following failure:

Compilation finished successfully


  TestToken contract
    Deployment
      1) "before each" hook for "Has the right name"


  0 passing (807ms)
  1 failing

  1) TestToken contract
       "before each" hook for "Has the right name":
     Error: Transaction reverted: function call to a non-contract account

Now, this does make perfect sense, after all I am attempting to call the Pancakeswap v2 router contract. How do I get around this limitation? Is there a way to inject the contract address for the router as an environment variable perhaps? Is there a mock constructor for the UniswapRouter I can be using? Generally, how is this sort of thing done in a way that remains testable (and how is it therefore tested) with smart contract development?

Solution

  • A hardhat test deploys the contracts to the hardhat local network (by default). This local network only has few pre-funded and unlocked accounts, but there are no smart contracts deployed. Including the PancakeSwap v2 Router (0x10ED43...).

    Instead of deploying and configuring local copy of the router contract, as well as all of its dependencies, you can create a new hardhat network forked from the production BSC.

    https://hardhat.org/guides/mainnet-forking.html

    This will run a local network with the Router contract available, but your actions will only effect the local network (not the mainnet).