Challenge - Multitoken Swapping

Contracts created:

• Swapper.sol
• TokenERC20.sol

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MUMBAI deployment address

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TokenA (TokenERC20.sol): 0xd70e89800bf481644914E677865990FF30Ffc9eD

TokenB (TokenERC20.sol): 0xbb29E734cc28C6433e53767b43D87386FA3d3140

TokenC (TokenERC20.sol): 0xD4ce82Fd648647DaD3AC8D89b5efA515f390C887

Swapper (Swapper.sol) : 0x19bB169e2EA6792EA926B74dFb2D8a77CDD9B458

Explorer: https://mumbai.polygonscan.com/

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Call Sequence

1. Deploy tokenA and tokenB contracts (both using TokenERC20.sol).
2. Deploy swapper contract (Swapper.sol). Take into account that tokenC contract is created by swapper contract at this step.
3. Mint enough tokens from tokenA and tokenB contracts (amount greater o equal than 100): tokenA.mint(receiver address, amount)
4. Approve tokenA and tokenB allowance for swapper contract (amount greater o equal than 100): tokenA.approve(swapper.address, amount)
5. Swap token A for token C: swapper.swap(tokenA.address, 100) // 1:1 - You receive 100 tokens C in exchange for 100 token A
6. Set a new price for token C as 2: swapper.setPriceTokenC(2) // Swap 2 tokens A or B x 1 token C
7. Swap token B for token C: swapper.swap(tokenB.address, 100) // 2:1 - You receive 50 tokens C in exchange for 100 token B
8. Approve token C allowance for swapper contract (amount greater o equal than 50):

   const addressTokenC = await swapper.getAddressTokenC();
   tokenC = await ethers.getContractAt("TokenERC20", addressTokenC);
   tokenC.approve(swapper.address, 50)

9. Unswap token B for token C: swapper.unswap(tokenB.address, 100) // 2:1 - You obtain 100 tokens B in exchange for 50 tokens C
10. Set a new price for token C as 1: swapper.setPriceTokenC(1) // Swap 1 token A or B x 1 token C
11. Approve token c allowance for swapper contract (amount greater o equal than 100): tokenC.approve(swapper.address, 100)
12. Unswap token A for token C: swapper.unswap(tokenA.address, 100) // 1:1 - You obtain 100 tokens A in exchange for 100 tokens C
13. At this step, the total supply for token C must be zero.

All these steps have been tested using the script test/test-swapper.js (It can be used as reference).

Commands:

• npm run test
• npx hardhat test