This is a mocha test case demostrating a bug with [sinon.test](http://sinonjs.org/docs/#sinon-test) whereby the sandbox gets restored before a promise-based async test completes.

sinon.test-with-promises.js

// sinon version 1.17.5
// Github issue: https://github.com/sinonjs/sinon/issues/1119
var sinon = require('sinon');

describe('sinon.test', function () {
    describe('with a promise', function () {
        it('does not restore the sandbox until the promise is fulfilled', sinon.test(function () {
            var sandbox = this;
            return Promise.resolve()
                .then(function () {
                    var mySpy = sandbox.spy(); // TypeError: sandbox.spy is not a function
                });
        }));
    });

    describe('with a done callback', function () {
        it('does not restore the sandbox until the callback is called', sinon.test(function (done) {
            var sandbox = this;
            Promise.resolve() // do something async
                .then(function () {
                    var mySpy = sandbox.spy(); // okay
                })
                .then(done)
                .catch(done);
        }));
    });
});