Add minutesBetween utility function

src/util/dates.js

@@ -114,6 +114,23 @@ export const daysBetween = (startDate, endDate) => {
   return days;
 };
 
+/**
+ * Calculate the number of minutes between the given dates
+ *
+ * @param {Date} startDate start of the time period
+ * @param {Date} endDate end of the time period.
+ *
+ * @throws Will throw if the end date is before the start date
+ * @returns {Number} number of minutes between the given Date objects
+ */
+export const minutesBetween = (startDate, endDate) => {
+  const minutes = moment(endDate).diff(startDate, 'minutes');
+  if (minutes < 0) {
+    throw new Error('End Date cannot be before start Date');
+  }
+  return minutes;
+};
+
 /**
  * Format the given date to month id/string
  *

src/util/dates.test.js

@@ -4,6 +4,7 @@ import {
   isSameDate,
   nightsBetween,
   daysBetween,
+  minutesBetween,
   formatDate,
   parseDateFromISO8601,
   stringifyDateToISO8601,
@@ -80,6 +81,28 @@ describe('date utils', () => {
     });
   });
 
+  describe('minutesBetween()', () => {
+    it('should fail if end Date is before start Date', () => {
+      const start = new Date(2017, 0, 2);
+      const end = new Date(2017, 0, 1);
+      expect(() => minutesBetween(start, end)).toThrow('End Date cannot be before start Date');
+    });
+    it('should handle equal start and end Dates', () => {
+      const d = new Date(2017, 0, 1, 10, 35, 0);
+      expect(minutesBetween(d, d)).toEqual(0);
+    });
+    it('should calculate minutes count for one hour', () => {
+      const start = new Date(2017, 0, 1, 10, 35, 0);
+      const end = new Date(2017, 0, 1, 11, 35, 0);
+      expect(minutesBetween(start, end)).toEqual(60);
+    });
+    it('should calculate minutes', () => {
+      const start = new Date(2017, 0, 1, 10, 35, 0);
+      const end = new Date(2017, 0, 1, 10, 55, 0);
+      expect(minutesBetween(start, end)).toEqual(20);
+    });
+  });
+
   describe('formatDate()', () => {
     /*
       NOTE: These are not really testing the formatting properly since