MCarlomagno

  it('deployed successfully', async () => {
    const address = await this.contract.address
    assert.notEqual(address, 0x0)
    assert.notEqual(address, '')
    assert.notEqual(address, null)
    assert.notEqual(address, undefined)
  })

MCarlomagno

// SPDX-License-Identifier: MIT
pragma solidity >=0.4.22 <0.9.0;

contract Persssist {
    string public name = "Persssist";
    uint256 public fileCount = 0;
    
    // this mapping behaves as a "catalog"
    // of files uploaded to the storage, we declare
    // it as public in order to access it directly from the Frontend

MCarlomagno

pragma solidity >=0.7.0 <0.9.0;

import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/cryptography/ECDSA.sol";
import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/utils/ReentrancyGuard.sol";

contract UniDirectionalPaymentChannel is ReentrancyGuard {
    using ECDSA for bytes32;

    address payable public sender;
    address payable public receiver;

MCarlomagno

    
pragma solidity >=0.7.0 <0.9.0;

import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/cryptography/ECDSA.sol";
import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/utils/ReentrancyGuard.sol";

contract UniDirectionalPaymentChannel is ReentrancyGuard {

    // ...
    

MCarlomagno

pragma solidity >=0.7.0 <0.9.0;

import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/cryptography/ECDSA.sol";
import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/utils/ReentrancyGuard.sol";

contract UniDirectionalPaymentChannel is ReentrancyGuard {
    
    // ...

    function _verify(uint _amount, bytes memory _sig) private view returns (bool) {

MCarlomagno

pragma solidity >=0.7.0 <0.9.0;

import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/cryptography/ECDSA.sol";
import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/utils/ReentrancyGuard.sol";

contract UniDirectionalPaymentChannel is ReentrancyGuard {
    
    // ...

    function _getHash(uint _amount) private view returns (bytes32) {

MCarlomagno

pragma solidity >=0.7.0 <0.9.0;

import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/cryptography/ECDSA.sol";
import "github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/utils/ReentrancyGuard.sol";

contract UniDirectionalPaymentChannel is ReentrancyGuard {
    using ECDSA for bytes32;

    address payable public sender;
    address payable public receiver;

MCarlomagno

  pragma solidity >=0.7.0 <0.9.0;

contract Chat {

  function sendMessage(string _text) public {
    lastMessageId++;

    // loads the message into the list.
    messageList[messageIdCounter] = Message(
      lastMessageId,

MCarlomagno

pragma solidity >=0.7.0 <0.9.0;

contract Chat {
    
  // the list of old messages in the chat
  mapping(uint => Message) public messagesList;
  function listMessages() public constant returns (uint[]){
    
    // if the chat is empty
    if(lastMessageId == 0) {

MCarlomagno

pragma solidity >=0.7.0 <0.9.0;

contract Chat {
  
  // ...
  
  // We can use an autoincremental id for each new message.
  uint lastMessageId;
  
  function sendMessage(string _text) public {