BDD

mocha.setup('bdd');

describe('something', function() {
  beforeEach(function() {
  });

  it('should work', function() {
  });
});

Async

it('should save', function(done) {
  var user = new User();
  user.save(function(err) {
    if (err) throw err;
    done();
  });
});

Chai: Shoulds

chai.should();

foo.should.be.a('string');
foo.should.equal('bar');
foo.should.have.length(3);
tea.should.have.property('flavors').with.length(3);

See also