--- /dev/null
+<?php
+
+namespace Drupal\Tests\user\Functional;
+
+use Drupal\Core\Datetime\Entity\DateFormat;
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Set a user time zone and verify that dates are displayed in local time.
+ *
+ * @group user
+ */
+class UserTimeZoneTest extends BrowserTestBase {
+
+ /**
+ * Modules to enable.
+ *
+ * @var array
+ */
+ public static $modules = ['node', 'system_test'];
+
+ /**
+ * Tests the display of dates and time when user-configurable time zones are set.
+ */
+ public function testUserTimeZone() {
+ // Setup date/time settings for Los Angeles time.
+ $this->config('system.date')
+ ->set('timezone.user.configurable', 1)
+ ->set('timezone.default', 'America/Los_Angeles')
+ ->save();
+
+ // Load the 'medium' date format, which is the default for node creation
+ // time, and override it. Since we are testing time zones with Daylight
+ // Saving Time, and need to future proof against changes to the zoneinfo
+ // database, we choose the 'I' format placeholder instead of a
+ // human-readable zone name. With 'I', a 1 means the date is in DST, and 0
+ // if not.
+ DateFormat::load('medium')
+ ->setPattern('Y-m-d H:i I')
+ ->save();
+
+ // Create a user account and login.
+ $web_user = $this->drupalCreateUser();
+ $this->drupalLogin($web_user);
+
+ // Create some nodes with different authored-on dates.
+ // Two dates in PST (winter time):
+ $date1 = '2007-03-09 21:00:00 -0800';
+ $date2 = '2007-03-11 01:00:00 -0800';
+ // One date in PDT (summer time):
+ $date3 = '2007-03-20 21:00:00 -0700';
+ $this->drupalCreateContentType(['type' => 'article']);
+ $node1 = $this->drupalCreateNode(['created' => strtotime($date1), 'type' => 'article']);
+ $node2 = $this->drupalCreateNode(['created' => strtotime($date2), 'type' => 'article']);
+ $node3 = $this->drupalCreateNode(['created' => strtotime($date3), 'type' => 'article']);
+
+ // Confirm date format and time zone.
+ $this->drupalGet('node/' . $node1->id());
+ $this->assertText('2007-03-09 21:00 0', 'Date should be PST.');
+ $this->drupalGet('node/' . $node2->id());
+ $this->assertText('2007-03-11 01:00 0', 'Date should be PST.');
+ $this->drupalGet('node/' . $node3->id());
+ $this->assertText('2007-03-20 21:00 1', 'Date should be PDT.');
+
+ // Change user time zone to Santiago time.
+ $edit = [];
+ $edit['mail'] = $web_user->getEmail();
+ $edit['timezone'] = 'America/Santiago';
+ $this->drupalPostForm("user/" . $web_user->id() . "/edit", $edit, t('Save'));
+ $this->assertText(t('The changes have been saved.'), 'Time zone changed to Santiago time.');
+
+ // Confirm date format and time zone.
+ $this->drupalGet('node/' . $node1->id());
+ $this->assertText('2007-03-10 02:00 1', 'Date should be Chile summer time; five hours ahead of PST.');
+ $this->drupalGet('node/' . $node2->id());
+ $this->assertText('2007-03-11 05:00 0', 'Date should be Chile time; four hours ahead of PST');
+ $this->drupalGet('node/' . $node3->id());
+ $this->assertText('2007-03-21 00:00 0', 'Date should be Chile time; three hours ahead of PDT.');
+
+ // Ensure that anonymous users also use the default timezone.
+ $this->drupalLogout();
+ $this->drupalGet('node/' . $node1->id());
+ $this->assertText('2007-03-09 21:00 0', 'Date should be PST.');
+ $this->drupalGet('node/' . $node2->id());
+ $this->assertText('2007-03-11 01:00 0', 'Date should be PST.');
+ $this->drupalGet('node/' . $node3->id());
+ $this->assertText('2007-03-20 21:00 1', 'Date should be PDT.');
+
+ // Format a date without accessing the current user at all and
+ // ensure that it uses the default timezone.
+ $this->drupalGet('/system-test/date');
+ $this->assertText('2016-01-13 08:29 0', 'Date should be PST.');
+ }
+
+}