Start and shutdown of test server more robust

    var server, lastResponseBody;

    before(function () {

    before(function (done) {

        // This creates a local server to test for various status codes. A request to /404 returns a 404, etc

        server = http.createServer(function(request, response){

            var path = url.parse(request.url).pathname;

            lastResponseBody = request.method + ' ' + request.url;

            response.end(lastResponseBody);

        });

        server.listen(4000);

        server.listen(4000, function () {

            done();

        });

    });

    after(function () {

        // Wait for all requests to finish since they may produce unhandled errors for tests at the end that don't wait themselves.

        setTimeout(function () {

            server.close();

        }, 20);

    });

    });

    describe('defaults', function () {});

    describe('defaults', function () {}); // TODO

    describe('should still allow a callback', function () {

        it('but not allow the then method to be invoked more than once', function () {

            var req = rp('http://localhost:4000/200');

            req.then(function () {}, function () {});

            // FIXME: Using the following line instead of the previous one produces an error.

//            req.then(function () {});

            req.then();

            expect(function () { req.then(); }).to.throw('Request-Promise currently only allows to call the rp(...).then(...) method once. Please use chaining like rp(...).then(...).then(...) instead.');

        });