• Ethereum Vault
  • 1. About
  • 2. Project description
  • 3. Smart contracts
  • 4. Install
  • 5. Running tests
    • Testing in Ganache
    • Testing in Kovan
    • Test suite output
  • 6. Deployed contracts in Kovan testnet
  • 7. TODO

This repository contains the source code and dependencies required to deploy a Solidity based VAULT smart contract that securely holds ETH whilst lending STABLE TOKEN to users on Ethereum network.

This project implements a Vault that allows a user to borrow a stable token (pegged to USD) by depositing ether into the Vault as collateral.

The amount of tokens that can be borrowed is derived from the ETH/USD price provided by an on-chain oracle.

The user is allowed to withdraw the collateral after repaying the borrowed tokens.

The amount of collateral available to withdraw depends on the current ETH/USD price provided by the Oracle.

The diagram below shows a high level overview with the main components and its interactions

The smart contracts in the project are:

Vault.sol

• implements the business logic of the Vault
• exposes 5 main functions

deposit(uint256 amountToDeposit) // Allows a user to deposit ETH collateral in exchange for some amount of stablecoin
withdraw(uint256 repaymentAmount)  // Allows a user to withdraw up to 100% of the collateral they have on deposit
getVault(address userAddress) //Returns the details of a vault
estimateCollateralAmount(uint256 repaymentAmount) // Returns an estimate of how much collateral could be withdrawn for a given amount of stablecoin
estimateTokenAmount(uint256 depositAmount) // Returns an estimate on how much stable coin could be minted at the current rate

Coin.sol

• ERC20 standard token
• implemens mint and burn

PriceConsumerV3.sol

• On chain oracle
• Leverages on chainlink price feed

Truffle and Ganache are required to deploy and test this project. They can be installed by running:

$ npm install -g truffle
$ npm install -g ganache-cli

Clone the repository and install dependencies:

$ npm install

This project includes a test suite based in Truffle/Mocha.

Tests can be run on local Ganache or on Kovan.

To run test in Ganache environment, a Ganache instance must be running on port 7545

You can start Ganache by executing the following:

$ ganache-cli -p 7545

To execute test suite, on a different terminal run:

truffle test --network development

The following is required to run test cases in Kovan network

• infura account

  API project KEY from https://infura.io enabled on KOVAN endpoint

• Kovan ether funds available

  At least 2 funded accounts are needed to run the tests in Kovan network.

  Ether funds in Kovan can be requested via Kovan faucet: https://faucet.kovan.network/

• .env file

  Truffle reads the kovan accounts and infura API KEY from a plain text .env file located in root folder.

  The .env file should define MNEMONIC and INFURA_APIKEY as environment variables:

MNEMONIC="<your mnemonic seed phrase that derives Kovan addresses with funds>"
INFURA_APIKEY="<your valid infura API key>"

To execute test suite run:

export TEST_NETWORK="kovan"
truffle test --network kovan

The following is the expected test result:

❯ export TEST_NETWORK="kovan"
❯ truffle test --network kovan
Using network 'kovan'.


Compiling your contracts...
===========================
✔ Fetching solc version list from solc-bin. Attempt #1
> Everything is up to date, there is nothing to compile.



  Contract: Vault
    Use Case 1: user deposits ether and receives stablecoin
      ✓ should update user Vault collateral with sent Ether (1142ms)
      ✓ should fire a 'Deposit' event
      ✓ should update user token balance (1244ms)
      ✓ should update user Vault debt (1289ms)
      ✓ should provide a estimated token amount with accuracy > 90% (1237ms)
    Use Case 2: user repays ALL tokens and withdraws ether
      ✓ should fire a 'Withdraw' event
      ✓ user token balance should be zero
      ✓ user vault debt should be zero (999ms)
      ✓ should provide a estimated repayment amount with accuracy > 90% (1143ms)


  9 passing (1m)

These contracts have been deployed in Kovan at the following addreses:

Vault.sol: https://kovan.etherscan.io/address/0xf9bf6096c67f643d4a8d407df12e3546e402cbc9

Coin.sol: https://kovan.etherscan.io/address/0xec8e0bb9169763d49349e459641595aed41e45c6

PriceConsumerV3.sol: https://kovan.etherscan.io/address/0x2699f2d5def11f16b6a357d133cda75cfde106b0

• Add collateralization ratio
• Implement liquidation
• Use safemath
• Improve test suite coverage
• Gas optimization
• Improve README.md

Credit for original repo goes to https://github.com/alejoacosta74/ethereum-erc20token-vault