There are a few ways to do testing of Solidity contracts. The easiest, at least in my opinion, is blackbox testing with Truffle. Contracts tend to be relatively small and self-contained, so blackbox testing seems appropriate here.
Truffle lets you write unit tests in Javascript using Pudding, an extension of web3, Mocha and Chai. A typical test looks like this:
contract('MetaCoin', function(accounts) { it("should put 10000 MetaCoin in the first account", function(done) { // Get a reference to the deployed MetaCoin contract, as a JS object. var meta = MetaCoin.deployed(); // Get the MetaCoin balance of the first account, and assert that it's 10000. meta.getBalance.call(accounts[0]).then(function(balance) { assert.equal(balance.valueOf(), 10000, "10000 wasn't in the first account"); }).then(done).catch(done); }); });