use truffle

contracts/ConvertLib.sol

+library ConvertLib{
+	function convert(uint amount,uint conversionRate) returns (uint convertedAmount)
+	{
+		return amount * conversionRate;
+	}
+}
\ No newline at end of file

contracts/MetaCoin.sol

+import "ConvertLib.sol";
+
+// This is just a simple example of a coin-like contract.
+// It is not standards compatible and cannot be expected to talk to other
+// coin/token contracts. If you want to create a standards-compliant
+// token, see: https://github.com/ConsenSys/Tokens. Cheers!
+
+contract MetaCoin {
+	mapping (address => uint) balances;
+
+	function MetaCoin() {
+		balances[tx.origin] = 10000;
+	}
+
+	function sendCoin(address receiver, uint amount) returns(bool sufficient) {
+		if (balances[msg.sender] < amount) return false;
+		balances[msg.sender] -= amount;
+		balances[receiver] += amount;
+		return true;
+	}
+
+	function getBalanceInEth(address addr) returns(uint){
+		return ConvertLib.convert(getBalance(addr),2);
+	}
+
+	function getBalance(address addr) returns(uint) {
+  	return balances[addr];
+	}
+}

contracts/Migrations.sol

+contract Migrations {
+  address public owner;
+  uint public last_completed_migration;
+
+  modifier restricted() {
+    if (msg.sender == owner) _
+  }
+
+  function Migrations() {
+    owner = msg.sender;
+  }
+
+  function setCompleted(uint completed) restricted {
+    last_completed_migration = completed;
+  }
+
+  function upgrade(address new_address) restricted {
+    Migrations upgraded = Migrations(new_address);
+    upgraded.setCompleted(last_completed_migration);
+  }
+}

migrations/1_initial_migration.js

+module.exports = function(deployer) {
+  deployer.deploy(Migrations);
+};

migrations/2_deploy_contracts.js

+module.exports = function(deployer) {
+  deployer.deploy(ConvertLib);
+  deployer.autolink();
+  deployer.deploy(MetaCoin);
+};

test/metacoin.js

+contract('MetaCoin', function(accounts) {
+  it("should put 10000 MetaCoin in the first account", function() {
+    var meta = MetaCoin.deployed();
+
+    return meta.getBalance.call(accounts[0]).then(function(balance) {
+      assert.equal(balance.valueOf(), 10000, "10000 wasn't in the first account");
+    });
+  });
+  it("should call a function that depends on a linked library  ", function(){
+    var meta = MetaCoin.deployed();
+    var metaCoinBalance;
+    var metaCoinEthBalance;
+
+    return meta.getBalance.call(accounts[0]).then(function(outCoinBalance){
+      metaCoinBalance = outCoinBalance.toNumber();
+      return meta.getBalanceInEth.call(accounts[0]);
+    }).then(function(outCoinBalanceEth){
+      metaCoinEthBalance = outCoinBalanceEth.toNumber();
+
+    }).then(function(){
+      assert.equal(metaCoinEthBalance,2*metaCoinBalance,"Library function returned unexpeced function, linkage may be broken");
+
+    });
+  });
+  it("should send coin correctly", function() {
+    var meta = MetaCoin.deployed();
+
+    // Get initial balances of first and second account.
+    var account_one = accounts[0];
+    var account_two = accounts[1];
+
+    var account_one_starting_balance;
+    var account_two_starting_balance;
+    var account_one_ending_balance;
+    var account_two_ending_balance;
+
+    var amount = 10;
+
+    return meta.getBalance.call(account_one).then(function(balance) {
+      account_one_starting_balance = balance.toNumber();
+      return meta.getBalance.call(account_two);
+    }).then(function(balance) {
+      account_two_starting_balance = balance.toNumber();
+      return meta.sendCoin(account_two, amount, {from: account_one});
+    }).then(function() {
+      return meta.getBalance.call(account_one);
+    }).then(function(balance) {
+      account_one_ending_balance = balance.toNumber();
+      return meta.getBalance.call(account_two);
+    }).then(function(balance) {
+      account_two_ending_balance = balance.toNumber();
+
+      assert.equal(account_one_ending_balance, account_one_starting_balance - amount, "Amount wasn't correctly taken from the sender");
+      assert.equal(account_two_ending_balance, account_two_starting_balance + amount, "Amount wasn't correctly sent to the receiver");
+    });
+  });
+});

truffle.js

+module.exports = {
+  build: {
+    "index.html": "index.html",
+    "app.js": [
+      "javascripts/app.js"
+    ],
+    "app.css": [
+      "stylesheets/app.css"
+    ],
+    "images/": "images/"
+  },
+  rpc: {
+    host: "localhost",
+    port: 8545
+  }
+};