Fix January unit test (#1417)

lib/text-formatters.spec.js

@@ -1,7 +1,7 @@
 'use strict';
 
 const { test, given } = require('sazerac');
-const moment = require('moment');
+const sinon = require('sinon');
 const {
   starRating,
   currencyFromCode,
@@ -76,6 +76,15 @@ describe('Text formatters', function() {
 
   test(formatDate, () => {
     given(1465513200000).describe('when given a timestamp in june 2016').expect('june 2016');
-    given(moment().startOf('year')).describe('when given the beginning of this year').expect('january');
+  });
+
+  context('in october', function () {
+    beforeEach(function () {
+      sinon.useFakeTimers(new Date(2017, 9, 15).getTime());
+    });
+
+    test(formatDate, () => {
+      given(new Date(2017, 0, 1).getTime()).describe('when given the beginning of this year').expect('january');
+    });
   });
 });