update interval module, add tests

test/src/helpers/index_timestamp.js

@@ -0,0 +1,62 @@
+import expect from 'expect.js';
+import sinon from 'sinon';
+import moment from 'moment';
+import proxyquire from 'proxyquire';
+
+const anchor = '2016-04-02T01:02:03.456'; // saturday
+
+const module = proxyquire.noPreserveCache()('../../../lib/helpers/index_timestamp', {
+  moment: () => moment(anchor)
+});
+const indexTimestamp = module.default;
+
+describe('Index interval', function () {
+  describe('indexTimestamp construction', function () {
+    it('should throw given an invalid interval', function () {
+      const init = () => indexTimestamp('bananas');
+      expect(init).to.throwException(/invalid.+interval/i);
+    });
+  });
+
+  describe('indexTimestamp timestamps', function () {
+    let clock;
+
+    beforeEach(function () {
+      clock = sinon.useFakeTimers(moment(anchor).valueOf());
+    });
+
+    afterEach(function () {
+      clock.restore();
+    });
+
+    it('should return the year', function () {
+      var timestamp = indexTimestamp('year');
+      expect(timestamp).to.equal('2016');
+    });
+
+    it('should return the year and month', function () {
+      var timestamp = indexTimestamp('month');
+      expect(timestamp).to.equal('2016-04');
+    });
+
+    it('should return the year, month, and first day of the week', function () {
+      var timestamp = indexTimestamp('week');
+      expect(timestamp).to.equal('2016-03-27');
+    });
+
+    it('should return the year, month, and day of the week', function () {
+      var timestamp = indexTimestamp('day');
+      expect(timestamp).to.equal('2016-04-02');
+    });
+
+    it('should return the year, month, day and hour', function () {
+      var timestamp = indexTimestamp('hour');
+      expect(timestamp).to.equal('2016-04-02-01');
+    });
+
+    it('should return the year, month, day, hour and minute', function () {
+      var timestamp = indexTimestamp('minute');
+      expect(timestamp).to.equal('2016-04-02-01-02');
+    });
+  });
+});