first commit

contracts/helper/Migrations.sol

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+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+pragma experimental ABIEncoderV2;
+
+
+contract Migrations {
+    address public owner;
+    uint256 public last_completed_migration;
+
+    modifier restricted() {
+        if (msg.sender == owner) {
+            _;
+        }
+    }
+
+    constructor() public {
+        owner = msg.sender;
+    }
+
+    function setCompleted(uint256 completed) public restricted {
+        last_completed_migration = completed;
+    }
+
+    function upgrade(address newAddress) public restricted {
+        Migrations upgraded = Migrations(newAddress);
+        upgraded.setCompleted(last_completed_migration);
+    }
+}

contracts/helper/NaiveOracle.sol

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+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+pragma experimental ABIEncoderV2;
+
+import {Ownable} from "../lib/Ownable.sol";
+
+
+// Oracle only for test
+contract NaiveOracle is Ownable {
+    uint256 public tokenPrice;
+
+    function setPrice(uint256 newPrice) external onlyOwner {
+        tokenPrice = newPrice;
+    }
+
+    function getPrice() external view returns (uint256) {
+        return tokenPrice;
+    }
+}

contracts/helper/TestERC20.sol

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+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+
+import {SafeMath} from "../lib/SafeMath.sol";
+
+
+contract TestERC20 {
+    using SafeMath for uint256;
+
+    mapping(address => uint256) balances;
+    mapping(address => mapping(address => uint256)) internal allowed;
+
+    event Transfer(address indexed from, address indexed to, uint256 amount);
+    event Approval(address indexed owner, address indexed spender, uint256 amount);
+
+    function transfer(address to, uint256 amount) public returns (bool) {
+        require(to != address(0), "TO_ADDRESS_IS_EMPTY");
+        require(amount <= balances[msg.sender], "BALANCE_NOT_ENOUGH");
+
+        balances[msg.sender] = balances[msg.sender].sub(amount);
+        balances[to] = balances[to].add(amount);
+        emit Transfer(msg.sender, to, amount);
+        return true;
+    }
+
+    function balanceOf(address owner) public view returns (uint256 balance) {
+        return balances[owner];
+    }
+
+    function transferFrom(
+        address from,
+        address to,
+        uint256 amount
+    ) public returns (bool) {
+        require(to != address(0), "TO_ADDRESS_IS_EMPTY");
+        require(amount <= balances[from], "BALANCE_NOT_ENOUGH");
+        require(amount <= allowed[from][msg.sender], "ALLOWANCE_NOT_ENOUGH");
+
+        balances[from] = balances[from].sub(amount);
+        balances[to] = balances[to].add(amount);
+        allowed[from][msg.sender] = allowed[from][msg.sender].sub(amount);
+        emit Transfer(from, to, amount);
+        return true;
+    }
+
+    function approve(address spender, uint256 amount) public returns (bool) {
+        allowed[msg.sender][spender] = amount;
+        emit Approval(msg.sender, spender, amount);
+        return true;
+    }
+
+    function allowance(address owner, address spender) public view returns (uint256) {
+        return allowed[owner][spender];
+    }
+
+    function mint(address account, uint256 amount) external {
+        balances[account] = balances[account].add(amount);
+    }
+}

contracts/helper/TestWETH.sol

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+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+
+
+contract WETH9 {
+    string public name = "Wrapped Ether";
+    string public symbol = "WETH";
+    uint8 public decimals = 18;
+
+    event Approval(address indexed src, address indexed guy, uint256 wad);
+    event Transfer(address indexed src, address indexed dst, uint256 wad);
+    event Deposit(address indexed dst, uint256 wad);
+    event Withdrawal(address indexed src, uint256 wad);
+
+    mapping(address => uint256) public balanceOf;
+    mapping(address => mapping(address => uint256)) public allowance;
+
+    fallback() external payable {
+        deposit();
+    }
+
+    receive() external payable {
+        deposit();
+    }
+
+    function deposit() public payable {
+        balanceOf[msg.sender] += msg.value;
+        emit Deposit(msg.sender, msg.value);
+    }
+
+    function withdraw(uint256 wad) public {
+        require(balanceOf[msg.sender] >= wad);
+        balanceOf[msg.sender] -= wad;
+        msg.sender.transfer(wad);
+        emit Withdrawal(msg.sender, wad);
+    }
+
+    function totalSupply() public view returns (uint256) {
+        return address(this).balance;
+    }
+
+    function approve(address guy, uint256 wad) public returns (bool) {
+        allowance[msg.sender][guy] = wad;
+        emit Approval(msg.sender, guy, wad);
+        return true;
+    }
+
+    function transfer(address dst, uint256 wad) public returns (bool) {
+        return transferFrom(msg.sender, dst, wad);
+    }
+
+    function transferFrom(
+        address src,
+        address dst,
+        uint256 wad
+    ) public returns (bool) {
+        require(balanceOf[src] >= wad);
+
+        if (src != msg.sender && allowance[src][msg.sender] != uint256(-1)) {
+            require(allowance[src][msg.sender] >= wad);
+            allowance[src][msg.sender] -= wad;
+        }
+
+        balanceOf[src] -= wad;
+        balanceOf[dst] += wad;
+
+        Transfer(src, dst, wad);
+
+        return true;
+    }
+}