Add documentation and a unit test for returning multiple arrays in a smocked function

[wei3erHase]

When trying to mock an UniswapV3Pool, to be accessed through the Oracle library, we're pointing to the observe(secondsAgo) function.

Code to be used in our contract:
(int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s) = IUniswapV3Pool(pool).observe(secondsAgos);

UniswapV3Pool.sol :

Oracle.Observation[65535] public override observations;
    [...]
    /// LINE 236
    function observe(uint32[] calldata secondsAgos)
        external
        view
        override
        noDelegateCall
        returns (int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s)
    {  ...  }

When trying to smock the answer of the address, have tried multiple options:
pool.smocked.observe.will.return.with([ 1, 1 ])
pool.smocked.observe.will.return.with([ [1], [1] ])

'tickCumulatives':1,
'secondsPerLiquidityCumulativeX128s':1
})

pool.smocked.observe.will.return.with({
'tickCumulatives':[1,2,3],
'secondsPerLiquidityCumulativeX128s':[1,2,3]
})

I've tried also replacing the numbers with BigNumber.from(0) but still, every try I'm getting the following error Error: Transaction reverted: function returned an unexpected amount of data

[smartcontracts]

Hmmm 🤔 nice catch. I assume the ideal syntax here is return.with([ 1234 ], [ 5678 ]) or alternatively the same thing with the return value wrapped in an array. I'll do some testing and see why this isn't working correctly.

[smartcontracts]

Hmmm very weird. I can't seem to replicate this locally. What version of hardhat are you using and what version of smock are you using?

[wei3erHase]

return.with([ 1234 ], [ 5678 ]) doesn't seem to be compilable with typescript:

TSError: ⨯ Unable to compile TypeScript:
test/unit/UniV3PoolTest.spec.ts:27:50 - error TS2554: Expected 0-1 arguments, but got 2.
27     pool.smocked.observe.will.return.with([1234],[5678]);

I'm using:

    "hardhat": "2.4.1",
    "@typechain/hardhat": "2.1.1",
    "@eth-optimism/smock": "1.1.6",

[wei3erHase]

A test contract:

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.6 <0.8.0;

import '@uniswap/v3-core/contracts/interfaces/IUniswapV3Pool.sol';

contract QuoterTest {
  address public token;
  address public weth;
  address public uniswapV3Pool;

  constructor(
    address _token,
    address _weth,
    address _uniswapV3Pool
  ) {
    token = _token;
    weth = _weth;
    uniswapV3Pool = _uniswapV3Pool;
  }

  uint32 public constant TWAP_PERIOD = 1 days;

  function observe(uint32[] calldata secondsAgos) public view returns (int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s) {
    (tickCumulatives, secondsPerLiquidityCumulativeX128s) = IUniswapV3Pool(uniswapV3Pool).observe(secondsAgos);
  }
}

A unit test:

import { ethers } from 'hardhat';
import { BigNumber, utils } from 'ethers';
import { smockit, MockContract } from '@eth-optimism/smock';
import { QuoterTest, QuoterTest__factory } from '@types';

import IUniswapV3Pool from '@uniswap/v3-core/contracts/interfaces/IUniswapV3Pool.sol/IUniswapV3Pool.json';
// import WeightedOracleLibrary from '@contracts/for-test/WeightedOracleLibraryForTest.sol/WeightedOracleLibrary.json';

describe.only('IQuoterTest', () => {
  let quoter: QuoterTest;
  let pool: MockContract;

  // examples for e2e checking
  const WETH = '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2';
  const TOKEN = '0x7fc66500c84a76ad7e9c93437bfc5ac33e2ddae9';
  const POOL = '0x5ab53ee1d50eef2c1dd3d5402789cd27bb52c1bb';

  beforeEach(async () => {
    pool = await smockit(IUniswapV3Pool.abi);

    const quoterFactory = (await ethers.getContractFactory('QuoterTest')) as unknown as QuoterTest__factory;
    quoter = await quoterFactory.deploy(TOKEN, WETH, pool.address);

    // pool.observe >> (int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s)
    pool.smocked.observe.will.return.with([1234],[5678]);
  });

  it('should deploy ok');
  it('should observe token', async() => {
    console.log(await quoter.observe([1]));
  })
});

[wei3erHase]

Apparently will.return([ [1234] , [5678] ]) is getting the job done!
Thanks

[smartcontracts]

Glad you figured it out, sorry about that! I'll add a unit test for this and update the docs, then will close this issue. Sometimes I make NFTs for people who make issues and I'm glad someone is using smock so just drop an ETH address if you want a smock-related hand-drawn NFT 😅

[wei3erHase]

sure! Will be using it much more so I'm glad to receive such feedback,
0xBad58e133138549936D2576ebC33251bE841d3e9
can't wait to see what this is about 😮

[smartcontracts]

If you have any additional feedback, please let me know! I want to make smock as useful as possible :-)

[smartcontracts]

Sent! https://opensea.io/assets/0x495f947276749ce646f68ac8c248420045cb7b5e/34765029840658706893803010833957019895695699803719888420488474709252701683713