test included; contract refactored

contracts/Splitter.sol

@@ -1,24 +1,25 @@
 pragma solidity >=0.4.25 <0.6.0;
 
 contract Splitter {
-	mapping (address => uint) public balances;
+    event LogSplit(address indexed sender, address indexed bob, address indexed carol, uint amount);
+    event LogWithdrawn(address indexed who, uint amount);
 
-	event Transfer(address indexed _from, address indexed _to1, address indexed _to2, uint256 _value);
+	mapping (address => uint) public balances;
 
 	constructor() public {
 		balances[msg.sender] = 10000;
 	}
 
-	function sendSplitCoin(address receiver1, address receiver2, uint amount) public returns(bool sufficient) {
-		if (balances[msg.sender] < amount) return false;
-		balances[msg.sender] -= amount;
-		balances[receiver1] += amount/2;
-		balances[receiver2] += amount/2;
-		emit Transfer(msg.sender, receiver1, receiver2, amount);
-		return true;
-	}
+    function split(address bob, address carol) payable public {
 
-	function getBalance(address addr) public view returns(uint) {
-		return balances[addr];
-	}
+        require(bob != address(0));
+        require(carol != address(0));
+
+        uint half = msg.value / 2;
+        require(half > 0);
+        balances[bob] += half;
+        balances[carol] += msg.value - half;
+        // We do not log the balance, only the change.
+        emit LogSplit(msg.sender, bob, carol, msg.value);
+    }
 }

test/TestSplitter.sol

@@ -0,0 +1,32 @@
+pragma solidity >=0.5.0 <0.6.0;
+
+import "truffle/Assert.sol";
+import "truffle/DeployedAddresses.sol";
+import "../contracts/Splitter.sol";
+
+contract TestSplitter {
+
+    uint public initialBalance = 101 finney;
+    address bob = 0x0123456789012345678901234567890123456789;
+    address carol = 0x1234567890123456789012345678901234567890;
+
+    function testSplitEqualBobCarol() public {
+        Splitter splitter = new Splitter();
+
+        splitter.split.value(100 finney)(bob, carol);
+
+        Assert.equal(address(splitter).balance, 100 finney, "Splitter contract should have the Ether");
+        Assert.equal(splitter.balances(bob), 50 finney, "Bob should be owed the exact half");
+        Assert.equal(splitter.balances(carol), 50 finney, "Carol should be owed the exact half");
+    }
+
+    function testSplitUnequalBobCarol() public {
+        Splitter splitter = new Splitter();
+
+        splitter.split.value(200003)(bob, carol);
+
+        Assert.equal(address(splitter).balance, 200003, "Splitter contract should have the Ether");
+        Assert.equal(splitter.balances(bob), 100001, "Bob should be owed the smaller half");
+        Assert.equal(splitter.balances(carol), 100002, "Carol should be owed the larger half");
+    }
+}

truffle-config.js

@@ -1,5 +1,5 @@
 module.exports = {
-  
+  /*
   networks: {
     development: {    // this one is optional and reduces "failing fast" dummerweise
       host: "127.0.0.1",
@@ -22,5 +22,5 @@ module.exports = {
       network_id: "3"
     }
   }
-
+  */
 };