Upgrade to solidity 0.5.0

.gitignore

@@ -0,0 +1 @@
+node_modules

contracts/DappToken.sol

@@ -1,10 +1,10 @@
-pragma solidity ^0.4.2;
+pragma solidity ^0.5.0;
 
 contract DappToken {
     string  public name = "DApp Token";
     string  public symbol = "DAPP";
     string  public standard = "DApp Token v1.0";
-    uint256 public totalSupply;
+    uint256 public totalSupply = 75000;
 
     event Transfer(
         address indexed _from,
@@ -21,40 +21,40 @@ contract DappToken {
     mapping(address => uint256) public balanceOf;
     mapping(address => mapping(address => uint256)) public allowance;
 
-    function DappToken (uint256 _initialSupply) public {
+    constructor (uint256 _initialSupply) public {
         balanceOf[msg.sender] = _initialSupply;
         totalSupply = _initialSupply;
     }
 
     function transfer(address _to, uint256 _value) public returns (bool success) {
-        require(balanceOf[msg.sender] >= _value);
+        require(balanceOf[msg.sender] >= _value, "Insufficient sender balance");
 
         balanceOf[msg.sender] -= _value;
         balanceOf[_to] += _value;
 
-        Transfer(msg.sender, _to, _value);
+        emit Transfer(msg.sender, _to, _value);
 
         return true;
     }
 
     function approve(address _spender, uint256 _value) public returns (bool success) {
         allowance[msg.sender][_spender] = _value;
 
-        Approval(msg.sender, _spender, _value);
+        emit Approval(msg.sender, _spender, _value);
 
         return true;
     }
 
     function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
-        require(_value <= balanceOf[_from]);
-        require(_value <= allowance[_from][msg.sender]);
+        require(_value <= balanceOf[_from], 'Amount should not exceed balance');
+        require(_value <= allowance[_from][msg.sender], 'Amount should not exceed allowance');
 
         balanceOf[_from] -= _value;
         balanceOf[_to] += _value;
 
         allowance[_from][msg.sender] -= _value;
 
-        Transfer(_from, _to, _value);
+        emit Transfer(_from, _to, _value);
 
         return true;
     }

contracts/DappTokenSale.sol

@@ -1,16 +1,17 @@
-pragma solidity ^0.4.2;
+pragma solidity ^0.5.0;
 
 import "./DappToken.sol";
 
 contract DappTokenSale {
-    address admin;
+    address payable admin;
     DappToken public tokenContract;
     uint256 public tokenPrice;
     uint256 public tokensSold;
 
     event Sell(address _buyer, uint256 _amount);
+    event EndSale(uint256 _totalAmountSold);
 
-    function DappTokenSale(DappToken _tokenContract, uint256 _tokenPrice) public {
+    constructor(DappToken _tokenContract, uint256 _tokenPrice) public {
         admin = msg.sender;
         tokenContract = _tokenContract;
         tokenPrice = _tokenPrice;
@@ -21,21 +22,24 @@ contract DappTokenSale {
     }
 
     function buyTokens(uint256 _numberOfTokens) public payable {
-        require(msg.value == multiply(_numberOfTokens, tokenPrice));
-        require(tokenContract.balanceOf(this) >= _numberOfTokens);
-        require(tokenContract.transfer(msg.sender, _numberOfTokens));
+        require(msg.value == multiply(_numberOfTokens, tokenPrice), 'msg.value must equal number of tokens in wei');
+        require(tokenContract.balanceOf(address(this)) >= _numberOfTokens, 'cannot purchase more tokens than available');
+        require(tokenContract.transfer(msg.sender, _numberOfTokens), 'Unable to send tokens');
+        // emit Balance(address(this), _numberOfTokens);
 
         tokensSold += _numberOfTokens;
 
-        Sell(msg.sender, _numberOfTokens);
+        emit Sell(msg.sender, _numberOfTokens);
     }
 
     function endSale() public {
         require(msg.sender == admin);
-        require(tokenContract.transfer(admin, tokenContract.balanceOf(this)));
-
+        require(tokenContract.transfer(admin, tokenContract.balanceOf(address(this))));
+        // require(tokenContract.transfer(admin, tokenContract.balanceOf(address(this))));
         // UPDATE: Let's not destroy the contract here
         // Just transfer the balance to the admin
         admin.transfer(address(this).balance);
+
+        emit EndSale(tokensSold);
     }
 }

contracts/Migrations.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.17;
+pragma solidity ^0.5.0;
 
 contract Migrations {
   address public owner;
@@ -8,7 +8,7 @@ contract Migrations {
     if (msg.sender == owner) _;
   }
 
-  function Migrations() public {
+  constructor() public {
     owner = msg.sender;
   }