Truffle 3.0 tests in async await

metacoin.js

var MetaCoin = artifacts.require("./MetaCoin.sol");

contract('MetaCoin', function(accounts) {

  it("should put 10000 MetaCoin in the first account", async function() {
    let meta = await MetaCoin.deployed();
    let balance = await meta.getBalance.call(accounts[0]);
    assert.equal(balance.valueOf(), 10000, "10000 wasn't in teh first account")
  });

  it("should call a function that depends on a linked library", async function() {
    let meta = await MetaCoin.deployed();
    let outCoinBalance = await meta.getBalance.call(accounts[0]);
    let outCoinBalanceEth = await meta.getBalanceInEth.call(accounts[0]);

    let metaCoinBalance = outCoinBalance.toNumber();
    let metaCoinEthBalance = outCoinBalanceEth.toNumber();

    assert.equal(metaCoinEthBalance, 2 * metaCoinBalance, "Library function returned unexpected function, linkage may be broken");
  });


  it("should send coin correctly", async function() {
    // Get initial balances of first and second account.
    var account_one = accounts[0];
    var account_two = accounts[1];

    var amount = 10;

    let meta = await MetaCoin.deployed();
    let balance1 = await meta.getBalance.call(account_one);
    let balance2 = await meta.getBalance.call(account_two);

    let account_one_starting_balance = balance1.toNumber();
    let account_two_starting_balance = balance2.toNumber();

    await meta.sendCoin(account_two, amount, {from: account_one});

    let balance3 = await meta.getBalance.call(account_one);
    let balance4 = await meta.getBalance.call(account_two);

    let account_one_ending_balance = balance3.toNumber();
    let account_two_ending_balance = balance4.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");
  });
});