From fe72ebd055ef0eedd85459ce6b36f504b3c33a3e Mon Sep 17 00:00:00 2001
From: Thijs Louisse <Thijs.Louisse@ing.com>
Date: Mon, 12 Aug 2019 09:37:48 +0200
Subject: [PATCH] fix(calendar): generated dates are normalized

---
 packages/calendar/src/LionCalendar.js           |  4 +++-
 .../calendar/src/utils/normalizeDateTime.js     |  9 +++++++++
 packages/calendar/test/lion-calendar.test.js    | 17 +++++++++++++++++
 .../test/utils/normalizeDateTime.test.js        | 16 ++++++++++++++++
 4 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 packages/calendar/src/utils/normalizeDateTime.js
 create mode 100644 packages/calendar/test/utils/normalizeDateTime.test.js

diff --git a/packages/calendar/src/LionCalendar.js b/packages/calendar/src/LionCalendar.js
index 737ddf1c5..f76641009 100644
--- a/packages/calendar/src/LionCalendar.js
+++ b/packages/calendar/src/LionCalendar.js
@@ -9,6 +9,7 @@ import { isSameDate } from './utils/isSameDate.js';
 import { calendarStyle } from './calendarStyle.js';
 import './utils/differentKeyNamesShimIE.js';
 import { createDay } from './utils/createDay.js';
+import { normalizeDateTime } from './utils/normalizeDateTime.js';
 
 /**
  * @customElement
@@ -152,7 +153,7 @@ export class LionCalendar extends LocalizeMixin(LitElement) {
     this.disableDates = () => false;
     this.firstDayOfWeek = 0;
     this.weekdayHeaderNotation = 'short';
-    this.__today = new Date();
+    this.__today = normalizeDateTime(new Date());
     this.centralDate = this.__today;
     this.__focusedDate = null;
     this.__connectedCallbackDone = false;
@@ -344,6 +345,7 @@ export class LionCalendar extends LocalizeMixin(LitElement) {
     if (this.minDate && day.date < this.minDate) {
       day.disabled = true;
     }
+
     if (this.maxDate && day.date > this.maxDate) {
       day.disabled = true;
     }
diff --git a/packages/calendar/src/utils/normalizeDateTime.js b/packages/calendar/src/utils/normalizeDateTime.js
new file mode 100644
index 000000000..de7e1d72f
--- /dev/null
+++ b/packages/calendar/src/utils/normalizeDateTime.js
@@ -0,0 +1,9 @@
+
+/**
+ * @desc Makes suitable for date comparisons
+ * @param {Date} d
+ * @returns {Date}
+ */
+export function normalizeDateTime(d) {
+  return new Date(d.getFullYear(), d.getMonth(), d.getDate());
+}
diff --git a/packages/calendar/test/lion-calendar.test.js b/packages/calendar/test/lion-calendar.test.js
index 56ea85fe0..e6438165b 100644
--- a/packages/calendar/test/lion-calendar.test.js
+++ b/packages/calendar/test/lion-calendar.test.js
@@ -338,6 +338,23 @@ describe('<lion-calendar>', () => {
 
         clock.restore();
       });
+
+      describe('Normalization', () => {
+        it('normalizes all generated dates', async () => {
+          function isNormalizedDate(d) {
+            return d.getHours() === 0 && d.getMinutes() === 0 && d.getSeconds() === 0;
+          }
+
+          const el = await fixture(
+            html`
+              <lion-calendar></lion-calendar>
+            `,
+          );
+          // The central date will be today's date: it's the date all other
+          // dates in the month view will be derived from.
+          expect(isNormalizedDate(el.centralDate)).to.be.true;
+        });
+      });
     });
   });
 
diff --git a/packages/calendar/test/utils/normalizeDateTime.test.js b/packages/calendar/test/utils/normalizeDateTime.test.js
new file mode 100644
index 000000000..f8121df9f
--- /dev/null
+++ b/packages/calendar/test/utils/normalizeDateTime.test.js
@@ -0,0 +1,16 @@
+import { expect } from '@open-wc/testing';
+import { normalizeDateTime } from '../../src/utils/normalizeDateTime.js';
+
+describe('normalizeDateTime', () => {
+  it('returns a date with hours, minutes and seconds set to 0', () => {
+    const date = normalizeDateTime(new Date('2000-11-29T12:34:56'));
+
+    expect(date.getFullYear()).to.equal(2000);
+    expect(date.getMonth()).to.equal(10);
+    expect(date.getDate()).to.equal(29);
+    // normalized parts
+    expect(date.getHours()).to.equal(0);
+    expect(date.getMinutes()).to.equal(0);
+    expect(date.getSeconds()).to.equal(0);
+  });
+});