diff core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php @ 0:4c8ae668cc8c

Initial import (non-working)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php	Wed Nov 29 16:09:58 2017 +0000
@@ -0,0 +1,855 @@
+<?php
+
+namespace Drupal\Tests\Component\Datetime;
+
+use Drupal\Component\Datetime\DateTimePlus;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @coversDefaultClass \Drupal\Component\Datetime\DateTimePlus
+ * @group Datetime
+ */
+class DateTimePlusTest extends TestCase {
+
+  /**
+   * Test creating dates from string and array input.
+   *
+   * @param mixed $input
+   *   Input argument for DateTimePlus.
+   * @param string $timezone
+   *   Timezone argument for DateTimePlus.
+   * @param string $expected
+   *   Expected output from DateTimePlus::format().
+   *
+   * @dataProvider providerTestDates
+   */
+  public function testDates($input, $timezone, $expected) {
+    $date = new DateTimePlus($input, $timezone);
+    $value = $date->format('c');
+
+    if (is_array($input)) {
+      $input = var_export($input, TRUE);
+    }
+    $this->assertEquals($expected, $value, sprintf("Test new DateTimePlus(%s, %s): should be %s, found %s.", $input, $timezone, $expected, $value));
+  }
+
+  /**
+   * Test creating dates from string and array input.
+   *
+   * @param mixed $input
+   *   Input argument for DateTimePlus.
+   * @param string $timezone
+   *   Timezone argument for DateTimePlus.
+   * @param string $expected
+   *   Expected output from DateTimePlus::format().
+   *
+   * @dataProvider providerTestDateArrays
+   */
+  public function testDateArrays($input, $timezone, $expected) {
+    $date = DateTimePlus::createFromArray($input, $timezone);
+    $value = $date->format('c');
+
+    if (is_array($input)) {
+      $input = var_export($input, TRUE);
+    }
+    $this->assertEquals($expected, $value, sprintf("Test new DateTimePlus(%s, %s): should be %s, found %s.", $input, $timezone, $expected, $value));
+  }
+
+  /**
+   * Test date diffs.
+   *
+   * @param mixed $input1
+   *   A DateTimePlus object.
+   * @param mixed $input2
+   *   Date argument for DateTimePlus::diff method.
+   * @param bool $absolute
+   *   Absolute flag for DateTimePlus::diff method.
+   * @param \DateInterval $expected
+   *   The expected result of the DateTimePlus::diff operation.
+   *
+   * @dataProvider providerTestDateDiff
+   */
+  public function testDateDiff($input1, $input2, $absolute, \DateInterval $expected) {
+    $interval = $input1->diff($input2, $absolute);
+    $this->assertEquals($interval, $expected);
+  }
+
+  /**
+   * Test date diff exception caused by invalid input.
+   *
+   * @param mixed $input1
+   *   A DateTimePlus object.
+   * @param mixed $input2
+   *   Date argument for DateTimePlus::diff method.
+   * @param bool $absolute
+   *   Absolute flag for DateTimePlus::diff method.
+   *
+   * @dataProvider providerTestInvalidDateDiff
+   */
+  public function testInvalidDateDiff($input1, $input2, $absolute) {
+    $this->setExpectedException(\BadMethodCallException::class, 'Method Drupal\Component\Datetime\DateTimePlus::diff expects parameter 1 to be a \DateTime or \Drupal\Component\Datetime\DateTimePlus object');
+    $interval = $input1->diff($input2, $absolute);
+  }
+
+  /**
+   * Test creating dates from invalid array input.
+   *
+   * @param mixed $input
+   *   Input argument for DateTimePlus.
+   * @param string $timezone
+   *   Timezone argument for DateTimePlus.
+   * @param string $class
+   *   The Exception subclass to expect to be thrown.
+   *
+   * @dataProvider providerTestInvalidDateArrays
+   */
+  public function testInvalidDateArrays($input, $timezone, $class) {
+    $this->setExpectedException($class);
+    $this->assertInstanceOf(
+      '\Drupal\Component\DateTimePlus',
+      DateTimePlus::createFromArray($input, $timezone)
+    );
+  }
+
+  /**
+   * Test creating dates from timestamps, and manipulating timezones.
+   *
+   * @param int $input
+   *   Input argument for DateTimePlus::createFromTimestamp().
+   * @param array $initial
+   *   An array containing:
+   *   - 'timezone_initial' - Timezone argument for DateTimePlus.
+   *   - 'format_initial' - Format argument for DateTimePlus.
+   *   - 'expected_initial_date' - Expected output from DateTimePlus::format().
+   *   - 'expected_initial_timezone' - Expected output from
+   *      DateTimePlus::getTimeZone()::getName().
+   *   - 'expected_initial_offset' - Expected output from DateTimePlus::getOffset().
+   * @param array $transform
+   *   An array containing:
+   *   - 'timezone_transform' - Argument to transform date to another timezone via
+   *     DateTimePlus::setTimezone().
+   *   - 'format_transform' - Format argument to use when transforming date to
+   *     another timezone.
+   *   - 'expected_transform_date' - Expected output from DateTimePlus::format(),
+   *     after timezone transform.
+   *   - 'expected_transform_timezone' - Expected output from
+   *     DateTimePlus::getTimeZone()::getName(), after timezone transform.
+   *   - 'expected_transform_offset' - Expected output from
+   *      DateTimePlus::getOffset(), after timezone transform.
+   *
+   * @dataProvider providerTestTimestamp
+   */
+  public function testTimestamp($input, array $initial, array $transform) {
+    // Initialize a new date object.
+    $date = DateTimePlus::createFromTimestamp($input, $initial['timezone']);
+    $this->assertDateTimestamp($date, $input, $initial, $transform);
+  }
+
+  /**
+   * Test creating dates from datetime strings.
+   *
+   * @param string $input
+   *   Input argument for DateTimePlus().
+   * @param array $initial
+   *   @see testTimestamp()
+   * @param array $transform
+   *   @see testTimestamp()
+   *
+   * @dataProvider providerTestDateTimestamp
+   */
+  public function testDateTimestamp($input, array $initial, array $transform) {
+    // Initialize a new date object.
+    $date = new DateTimePlus($input, $initial['timezone']);
+    $this->assertDateTimestamp($date, $input, $initial, $transform);
+  }
+
+  /**
+   * Assertion helper for testTimestamp and testDateTimestamp since they need
+   * different dataProviders.
+   *
+   * @param DateTimePlus $date
+   *   DateTimePlus to test.
+   * @input mixed $input
+   *   The original input passed to the test method.
+   * @param array $initial
+   *   @see testTimestamp()
+   * @param array $transform
+   *   @see testTimestamp()
+   */
+  public function assertDateTimestamp($date, $input, $initial, $transform) {
+    // Check format.
+    $value = $date->format($initial['format']);
+    $this->assertEquals($initial['expected_date'], $value, sprintf("Test new DateTimePlus(%s, %s): should be %s, found %s.", $input, $initial['timezone'], $initial['expected_date'], $value));
+
+    // Check timezone name.
+    $value = $date->getTimeZone()->getName();
+    $this->assertEquals($initial['expected_timezone'], $value, sprintf("The current timezone is %s: should be %s.", $value, $initial['expected_timezone']));
+
+    // Check offset.
+    $value = $date->getOffset();
+    $this->assertEquals($initial['expected_offset'], $value, sprintf("The current offset is %s: should be %s.", $value, $initial['expected_offset']));
+
+    // Transform the date to another timezone.
+    $date->setTimezone(new \DateTimeZone($transform['timezone']));
+
+    // Check transformed format.
+    $value = $date->format($transform['format']);
+    $this->assertEquals($transform['expected_date'], $value, sprintf("Test \$date->setTimezone(new \\DateTimeZone(%s)): should be %s, found %s.", $transform['timezone'], $transform['expected_date'], $value));
+
+    // Check transformed timezone.
+    $value = $date->getTimeZone()->getName();
+    $this->assertEquals($transform['expected_timezone'], $value, sprintf("The current timezone should be %s, found %s.", $transform['expected_timezone'], $value));
+
+    // Check transformed offset.
+    $value = $date->getOffset();
+    $this->assertEquals($transform['expected_offset'], $value, sprintf("The current offset should be %s, found %s.", $transform['expected_offset'], $value));
+  }
+
+  /**
+   * Test creating dates from format strings.
+   *
+   * @param string $input
+   *   Input argument for DateTimePlus.
+   * @param string $timezone
+   *   Timezone argument for DateTimePlus.
+   * @param string $format_date
+   *   Format argument for DateTimePlus::format().
+   * @param string $expected
+   *   Expected output from DateTimePlus::format().
+   *
+   * @dataProvider providerTestDateFormat
+   */
+  public function testDateFormat($input, $timezone, $format, $format_date, $expected) {
+    $date = DateTimePlus::createFromFormat($format, $input, $timezone);
+    $value = $date->format($format_date);
+    $this->assertEquals($expected, $value, sprintf("Test new DateTimePlus(%s, %s, %s): should be %s, found %s.", $input, $timezone, $format, $expected, $value));
+  }
+
+  /**
+   * Test invalid date handling.
+   *
+   * @param mixed $input
+   *   Input argument for DateTimePlus.
+   * @param string $timezone
+   *   Timezone argument for DateTimePlus.
+   * @param string $format
+   *   Format argument for DateTimePlus.
+   * @param string $message
+   *   Message to print if no errors are thrown by the invalid dates.
+   * @param string $class
+   *   The Exception subclass to expect to be thrown.
+   *
+   * @dataProvider providerTestInvalidDates
+   */
+  public function testInvalidDates($input, $timezone, $format, $message, $class) {
+    $this->setExpectedException($class);
+    DateTimePlus::createFromFormat($format, $input, $timezone);
+  }
+
+  /**
+   * Tests that DrupalDateTime can detect the right timezone to use.
+   * When specified or not.
+   *
+   * @param mixed $input
+   *   Input argument for DateTimePlus.
+   * @param mixed $timezone
+   *   Timezone argument for DateTimePlus.
+   * @param string $expected_timezone
+   *   Expected timezone returned from DateTimePlus::getTimezone::getName().
+   * @param string $message
+   *   Message to print on test failure.
+   *
+   * @dataProvider providerTestDateTimezone
+   */
+  public function testDateTimezone($input, $timezone, $expected_timezone, $message) {
+    $date = new DateTimePlus($input, $timezone);
+    $timezone = $date->getTimezone()->getName();
+    $this->assertEquals($timezone, $expected_timezone, $message);
+  }
+
+  /**
+   * Test that DrupalDateTime can detect the right timezone to use when
+   * constructed from a datetime object.
+   */
+  public function testDateTimezoneWithDateTimeObject() {
+    // Create a date object with another date object.
+    $input = new \DateTime('now', new \DateTimeZone('Pacific/Midway'));
+    $timezone = NULL;
+    $expected_timezone = 'Pacific/Midway';
+    $message = 'DateTimePlus uses the specified timezone if provided.';
+
+    $date = DateTimePlus::createFromDateTime($input, $timezone);
+    $timezone = $date->getTimezone()->getName();
+    $this->assertEquals($timezone, $expected_timezone, $message);
+  }
+
+  /**
+   * Provides data for date tests.
+   *
+   * @return array
+   *   An array of arrays, each containing the input parameters for
+   *   DateTimePlusTest::testDates().
+   *
+   * @see DateTimePlusTest::testDates()
+   */
+  public function providerTestDates() {
+    $dates = [
+      // String input.
+      // Create date object from datetime string.
+      ['2009-03-07 10:30', 'America/Chicago', '2009-03-07T10:30:00-06:00'],
+      // Same during daylight savings time.
+      ['2009-06-07 10:30', 'America/Chicago', '2009-06-07T10:30:00-05:00'],
+      // Create date object from date string.
+      ['2009-03-07', 'America/Chicago', '2009-03-07T00:00:00-06:00'],
+      // Same during daylight savings time.
+      ['2009-06-07', 'America/Chicago', '2009-06-07T00:00:00-05:00'],
+      // Create date object from date string.
+      ['2009-03-07 10:30', 'Australia/Canberra', '2009-03-07T10:30:00+11:00'],
+      // Same during daylight savings time.
+      ['2009-06-07 10:30', 'Australia/Canberra', '2009-06-07T10:30:00+10:00'],
+    ];
+
+    // On 32-bit systems, timestamps are limited to 1901-2038.
+    if (PHP_INT_SIZE > 4) {
+      // Create a date object in the distant past.
+      // @see https://www.drupal.org/node/2795489#comment-12127088
+      if (version_compare(PHP_VERSION, '5.6.15', '>=')) {
+        $dates[] = ['1809-02-12 10:30', 'America/Chicago', '1809-02-12T10:30:00-06:00'];
+      }
+      // Create a date object in the far future.
+      $dates[] = ['2345-01-02 02:04', 'UTC', '2345-01-02T02:04:00+00:00'];
+    }
+
+    return $dates;
+  }
+
+  /**
+   * Provides data for date tests.
+   *
+   * @return array
+   *   An array of arrays, each containing the input parameters for
+   *   DateTimePlusTest::testDates().
+   *
+   * @see DateTimePlusTest::testDates()
+   */
+  public function providerTestDateArrays() {
+    $dates = [
+      // Array input.
+      // Create date object from date array, date only.
+      [['year' => 2010, 'month' => 2, 'day' => 28], 'America/Chicago', '2010-02-28T00:00:00-06:00'],
+      // Create date object from date array with hour.
+      [['year' => 2010, 'month' => 2, 'day' => 28, 'hour' => 10], 'America/Chicago', '2010-02-28T10:00:00-06:00'],
+      // Create date object from date array, date only.
+      [['year' => 2010, 'month' => 2, 'day' => 28], 'Europe/Berlin', '2010-02-28T00:00:00+01:00'],
+      // Create date object from date array with hour.
+      [['year' => 2010, 'month' => 2, 'day' => 28, 'hour' => 10], 'Europe/Berlin', '2010-02-28T10:00:00+01:00'],
+    ];
+
+    // On 32-bit systems, timestamps are limited to 1901-2038.
+    if (PHP_INT_SIZE > 4) {
+      // Create a date object in the distant past.
+      // @see https://www.drupal.org/node/2795489#comment-12127088
+      if (version_compare(PHP_VERSION, '5.6.15', '>=')) {
+        $dates[] = [['year' => 1809, 'month' => 2, 'day' => 12], 'America/Chicago', '1809-02-12T00:00:00-06:00'];
+      }
+      // Create a date object in the far future.
+      $dates[] = [['year' => 2345, 'month' => 1, 'day' => 2], 'UTC', '2345-01-02T00:00:00+00:00'];
+    }
+
+    return $dates;
+  }
+
+  /**
+   * Provides data for testDateFormats.
+   *
+   * @return array
+   *   An array of arrays, each containing:
+   *   - 'input' - Input to DateTimePlus.
+   *   - 'timezone' - Timezone for DateTimePlus.
+   *   - 'format' - Date format for DateTimePlus.
+   *   - 'format_date' - Date format for use in $date->format() method.
+   *   - 'expected' - The expected return from DateTimePlus.
+   *
+   * @see testDateFormats()
+   */
+  public function providerTestDateFormat() {
+    return [
+      // Create a year-only date.
+      ['2009', NULL, 'Y', 'Y', '2009'],
+      // Create a month and year-only date.
+      ['2009-10', NULL, 'Y-m', 'Y-m', '2009-10'],
+      // Create a time-only date.
+      ['T10:30:00', NULL, '\TH:i:s', 'H:i:s', '10:30:00'],
+      // Create a time-only date.
+      ['10:30:00', NULL, 'H:i:s', 'H:i:s', '10:30:00'],
+    ];
+  }
+
+  /**
+   * Provides data for testInvalidDates.
+   *
+   * @return array
+   *   An array of arrays, each containing:
+   *   - 'input' - Input for DateTimePlus.
+   *   - 'timezone' - Timezone for DateTimePlus.
+   *   - 'format' - Format for DateTimePlus.
+   *   - 'message' - Message to display on failure.
+   *
+   * @see testInvalidDates
+   */
+  public function providerTestInvalidDates() {
+    return [
+      // Test for invalid month names when we are using a short version
+      // of the month.
+      ['23 abc 2012', NULL, 'd M Y', "23 abc 2012 contains an invalid month name and did not produce errors.", \InvalidArgumentException::class],
+      // Test for invalid hour.
+      ['0000-00-00T45:30:00', NULL, 'Y-m-d\TH:i:s', "0000-00-00T45:30:00 contains an invalid hour and did not produce errors.", \UnexpectedValueException::class],
+      // Test for invalid day.
+      ['0000-00-99T05:30:00', NULL, 'Y-m-d\TH:i:s', "0000-00-99T05:30:00 contains an invalid day and did not produce errors.", \UnexpectedValueException::class],
+      // Test for invalid month.
+      ['0000-75-00T15:30:00', NULL, 'Y-m-d\TH:i:s', "0000-75-00T15:30:00 contains an invalid month and did not produce errors.", \UnexpectedValueException::class],
+      // Test for invalid year.
+      ['11-08-01T15:30:00', NULL, 'Y-m-d\TH:i:s', "11-08-01T15:30:00 contains an invalid year and did not produce errors.", \UnexpectedValueException::class],
+
+    ];
+  }
+
+  /**
+   * Data provider for testInvalidDateArrays.
+   *
+   * @return array
+   *   An array of arrays, each containing:
+   *   - 'input' - Input for DateTimePlus.
+   *   - 'timezone' - Timezone for DateTimePlus.
+   *
+   * @see testInvalidDateArrays
+   */
+  public function providerTestInvalidDateArrays() {
+    return [
+      // One year larger than the documented upper limit of checkdate().
+      [['year' => 32768, 'month' => 1, 'day' => 8, 'hour' => 8, 'minute' => 0, 'second' => 0], 'America/Chicago', \InvalidArgumentException::class],
+      // One year smaller than the documented lower limit of checkdate().
+      [['year' => 0, 'month' => 1, 'day' => 8, 'hour' => 8, 'minute' => 0, 'second' => 0], 'America/Chicago', \InvalidArgumentException::class],
+      // Test for invalid month from date array.
+      [['year' => 2010, 'month' => 27, 'day' => 8, 'hour' => 8, 'minute' => 0, 'second' => 0], 'America/Chicago', \InvalidArgumentException::class],
+      // Test for invalid hour from date array.
+      [['year' => 2010, 'month' => 2, 'day' => 28, 'hour' => 80, 'minute' => 0, 'second' => 0], 'America/Chicago', \InvalidArgumentException::class],
+      // Test for invalid minute from date array.
+      [['year' => 2010, 'month' => 7, 'day' => 8, 'hour' => 8, 'minute' => 88, 'second' => 0], 'America/Chicago', \InvalidArgumentException::class],
+      // Regression test for https://www.drupal.org/node/2084455.
+      [['hour' => 59, 'minute' => 1, 'second' => 1], 'America/Chicago', \InvalidArgumentException::class],
+    ];
+  }
+
+  /**
+   * Provides data for testDateTimezone.
+   *
+   * @return array
+   *   An array of arrays, each containing:
+   *   - 'date' - Date string or object for DateTimePlus.
+   *   - 'timezone' - Timezone string for DateTimePlus.
+   *   - 'expected' - Expected return from DateTimePlus::getTimezone()::getName().
+   *   - 'message' - Message to display on test failure.
+   *
+   * @see testDateTimezone
+   */
+  public function providerTestDateTimezone() {
+    // Use a common date for most of the tests.
+    $date_string = '2007-01-31 21:00:00';
+
+    // Detect the system timezone.
+    $system_timezone = date_default_timezone_get();
+
+    return [
+      // Create a date object with an unspecified timezone, which should
+      // end up using the system timezone.
+      [$date_string, NULL, $system_timezone, 'DateTimePlus uses the system timezone when there is no site timezone.'],
+      // Create a date object with a specified timezone name.
+      [$date_string, 'America/Yellowknife', 'America/Yellowknife', 'DateTimePlus uses the specified timezone if provided.'],
+      // Create a date object with a timezone object.
+      [$date_string, new \DateTimeZone('Australia/Canberra'), 'Australia/Canberra', 'DateTimePlus uses the specified timezone if provided.'],
+      // Create a date object with another date object.
+      [new DateTimePlus('now', 'Pacific/Midway'), NULL, 'Pacific/Midway', 'DateTimePlus uses the specified timezone if provided.'],
+    ];
+  }
+
+  /**
+   * Provides data for testTimestamp.
+   *
+   * @return array
+   *   An array of arrays, each containing the arguments required for
+   *   self::testTimestamp().
+   *
+   * @see testTimestamp()
+   */
+  public function providerTestTimestamp() {
+    return [
+      // Create date object from a unix timestamp and display it in
+      // local time.
+      [
+        'input' => 0,
+        'initial' => [
+          'timezone' => 'UTC',
+          'format' => 'c',
+          'expected_date' => '1970-01-01T00:00:00+00:00',
+          'expected_timezone' => 'UTC',
+          'expected_offset' => 0,
+        ],
+        'transform' => [
+          'timezone' => 'America/Los_Angeles',
+          'format' => 'c',
+          'expected_date' => '1969-12-31T16:00:00-08:00',
+          'expected_timezone' => 'America/Los_Angeles',
+          'expected_offset' => '-28800',
+        ],
+      ],
+      // Create a date using the timestamp of zero, then display its
+      // value both in UTC and the local timezone.
+      [
+        'input' => 0,
+        'initial' => [
+          'timezone' => 'America/Los_Angeles',
+          'format' => 'c',
+          'expected_date' => '1969-12-31T16:00:00-08:00',
+          'expected_timezone' => 'America/Los_Angeles',
+          'expected_offset' => '-28800',
+        ],
+        'transform' => [
+          'timezone' => 'UTC',
+          'format' => 'c',
+          'expected_date' => '1970-01-01T00:00:00+00:00',
+          'expected_timezone' => 'UTC',
+          'expected_offset' => 0,
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * Provides data for testDateTimestamp.
+   *
+   * @return array
+   *   An array of arrays, each containing the arguments required for
+   *   self::testDateTimestamp().
+   *
+   * @see testDateTimestamp()
+   */
+  public function providerTestDateTimestamp() {
+    return [
+      // Create date object from datetime string in UTC, and convert
+      // it to a local date.
+      [
+        'input' => '1970-01-01 00:00:00',
+        'initial' => [
+          'timezone' => 'UTC',
+          'format' => 'c',
+          'expected_date' => '1970-01-01T00:00:00+00:00',
+          'expected_timezone' => 'UTC',
+          'expected_offset' => 0,
+        ],
+        'transform' => [
+          'timezone' => 'America/Los_Angeles',
+          'format' => 'c',
+          'expected_date' => '1969-12-31T16:00:00-08:00',
+          'expected_timezone' => 'America/Los_Angeles',
+          'expected_offset' => '-28800',
+        ],
+      ],
+      // Convert the local time to UTC using string input.
+      [
+        'input' => '1969-12-31 16:00:00',
+        'initial' => [
+          'timezone' => 'America/Los_Angeles',
+          'format' => 'c',
+          'expected_date' => '1969-12-31T16:00:00-08:00',
+          'expected_timezone' => 'America/Los_Angeles',
+          'expected_offset' => '-28800',
+        ],
+        'transform' => [
+          'timezone' => 'UTC',
+          'format' => 'c',
+          'expected_date' => '1970-01-01T00:00:00+00:00',
+          'expected_timezone' => 'UTC',
+          'expected_offset' => 0,
+        ],
+      ],
+      // Convert the local time to UTC using string input.
+      [
+        'input' => '1969-12-31 16:00:00',
+        'initial' => [
+          'timezone' => 'Europe/Warsaw',
+          'format' => 'c',
+          'expected_date' => '1969-12-31T16:00:00+01:00',
+          'expected_timezone' => 'Europe/Warsaw',
+          'expected_offset' => '+3600',
+        ],
+        'transform' => [
+          'timezone' => 'UTC',
+          'format' => 'c',
+          'expected_date' => '1969-12-31T15:00:00+00:00',
+          'expected_timezone' => 'UTC',
+          'expected_offset' => 0,
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * Provides data for date tests.
+   *
+   * @return array
+   *   An array of arrays, each containing the input parameters for
+   *   DateTimePlusTest::testDateDiff().
+   *
+   * @see DateTimePlusTest::testDateDiff()
+   */
+  public function providerTestDateDiff() {
+
+    $empty_interval = new \DateInterval('PT0S');
+
+    $positive_19_hours = new \DateInterval('PT19H');
+
+    $positive_18_hours = new \DateInterval('PT18H');
+
+    $positive_1_hour = new \DateInterval('PT1H');
+
+    $negative_1_hour = new \DateInterval('PT1H');
+    $negative_1_hour->invert = 1;
+
+    return [
+      // There should be a 19 hour time interval between
+      // new years in Sydney and new years in LA in year 2000.
+      [
+        'input2' => DateTimePlus::createFromFormat('Y-m-d H:i:s', '2000-01-01 00:00:00', new \DateTimeZone('Australia/Sydney')),
+        'input1' => DateTimePlus::createFromFormat('Y-m-d H:i:s', '2000-01-01 00:00:00', new \DateTimeZone('America/Los_Angeles')),
+        'absolute' => FALSE,
+        'expected' => $positive_19_hours,
+      ],
+      // In 1970 Sydney did not observe daylight savings time
+      // So there is only a 18 hour time interval.
+      [
+        'input2' => DateTimePlus::createFromFormat('Y-m-d H:i:s', '1970-01-01 00:00:00', new \DateTimeZone('Australia/Sydney')),
+        'input1' => DateTimePlus::createFromFormat('Y-m-d H:i:s', '1970-01-01 00:00:00', new \DateTimeZone('America/Los_Angeles')),
+        'absolute' => FALSE,
+        'expected' => $positive_18_hours,
+      ],
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 3600, new \DateTimeZone('America/Los_Angeles')),
+        'input2' => DateTimePlus::createFromFormat('U', 0, new \DateTimeZone('UTC')),
+        'absolute' => FALSE,
+        'expected' => $negative_1_hour,
+      ],
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input2' => DateTimePlus::createFromFormat('U', 0),
+        'absolute' => FALSE,
+        'expected' => $negative_1_hour,
+      ],
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input2' => \DateTime::createFromFormat('U', 0),
+        'absolute' => FALSE,
+        'expected' => $negative_1_hour,
+      ],
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input2' => DateTimePlus::createFromFormat('U', 0),
+        'absolute' => TRUE,
+        'expected' => $positive_1_hour,
+      ],
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input2' => \DateTime::createFromFormat('U', 0),
+        'absolute' => TRUE,
+        'expected' => $positive_1_hour,
+      ],
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 0),
+        'input2' => DateTimePlus::createFromFormat('U', 0),
+        'absolute' => FALSE,
+        'expected' => $empty_interval,
+      ],
+    ];
+  }
+
+  /**
+   * Provides data for date tests.
+   *
+   * @return array
+   *   An array of arrays, each containing the input parameters for
+   *   DateTimePlusTest::testInvalidDateDiff().
+   *
+   * @see DateTimePlusTest::testInvalidDateDiff()
+   */
+  public function providerTestInvalidDateDiff() {
+    return [
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input2' => '1970-01-01 00:00:00',
+        'absolute' => FALSE,
+      ],
+      [
+        'input1' => DateTimePlus::createFromFormat('U', 3600),
+        'input2' => NULL,
+        'absolute' => FALSE,
+      ],
+    ];
+  }
+
+  /**
+   * Tests invalid values passed to constructor.
+   *
+   * @param string $time
+   *   A date/time string.
+   * @param string[] $errors
+   *   An array of error messages.
+   *
+   * @covers ::__construct
+   *
+   * @dataProvider providerTestInvalidConstructor
+   */
+  public function testInvalidConstructor($time, array $errors) {
+    $date = new DateTimePlus($time);
+
+    $this->assertEquals(TRUE, $date->hasErrors());
+    $this->assertEquals($errors, $date->getErrors());
+  }
+
+  /**
+   * Provider for testInvalidConstructor().
+   *
+   * @return array
+   *   An array of invalid date/time strings, and corresponding error messages.
+   */
+  public function providerTestInvalidConstructor() {
+    return [
+      [
+        'YYYY-MM-DD',
+        [
+          'The timezone could not be found in the database',
+          'Unexpected character',
+          'Double timezone specification',
+        ],
+      ],
+      [
+        '2017-MM-DD',
+        [
+          'Unexpected character',
+          'The timezone could not be found in the database',
+        ],
+      ],
+      [
+        'YYYY-03-DD',
+        [
+          'The timezone could not be found in the database',
+          'Unexpected character',
+          'Double timezone specification',
+        ],
+      ],
+      [
+        'YYYY-MM-07',
+        [
+          'The timezone could not be found in the database',
+          'Unexpected character',
+          'Double timezone specification',
+        ],
+      ],
+      [
+        '2017-13-55',
+        [
+          'Unexpected character',
+        ],
+      ],
+      [
+        'YYYY-MM-DD hh:mm:ss',
+        [
+          'The timezone could not be found in the database',
+          'Unexpected character',
+          'Double timezone specification',
+        ],
+      ],
+      [
+        '2017-03-07 25:70:80',
+        [
+          'Unexpected character',
+          'Double time specification',
+        ],
+      ],
+      [
+        'lorem ipsum dolor sit amet',
+        [
+          'The timezone could not be found in the database',
+          'Double timezone specification',
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * Tests the $settings['validate_format'] parameter in ::createFromFormat().
+   */
+  public function testValidateFormat() {
+    // Check that an input that does not strictly follow the input format will
+    // produce the desired date. In this case the year string '11' doesn't
+    // precisely match the 'Y' formater parameter, but PHP will parse it
+    // regardless. However, when formatted with the same string, the year will
+    // be output with four digits. With the ['validate_format' => FALSE]
+    // $settings, this will not thrown an exception.
+    $date = DateTimePlus::createFromFormat('Y-m-d H:i:s', '11-03-31 17:44:00', 'UTC', ['validate_format' => FALSE]);
+    $this->assertEquals('0011-03-31 17:44:00', $date->format('Y-m-d H:i:s'));
+
+    // Parse the same date with ['validate_format' => TRUE] and make sure we
+    // get the expected exception.
+    $this->setExpectedException(\UnexpectedValueException::class);
+    $date = DateTimePlus::createFromFormat('Y-m-d H:i:s', '11-03-31 17:44:00', 'UTC', ['validate_format' => TRUE]);
+  }
+
+  /**
+   * Tests that object methods are chainable.
+   *
+   * @covers ::__call
+   */
+  public function testChainable() {
+    $date = new DateTimePlus('now', 'Australia/Sydney');
+
+    $date->setTimestamp(12345678);
+    $rendered = $date->render();
+    $this->assertEquals('1970-05-24 07:21:18 Australia/Sydney', $rendered);
+
+    $date->setTimestamp(23456789);
+    $rendered = $date->setTimezone(new \DateTimeZone('America/New_York'))->render();
+    $this->assertEquals('1970-09-29 07:46:29 America/New_York', $rendered);
+
+    $date = DateTimePlus::createFromFormat('Y-m-d H:i:s', '1970-05-24 07:21:18', new \DateTimeZone('Australia/Sydney'))
+      ->setTimezone(new \DateTimeZone('America/New_York'));
+    $rendered = $date->render();
+    $this->assertInstanceOf(DateTimePlus::class, $date);
+    $this->assertEquals(12345678, $date->getTimestamp());
+    $this->assertEquals('1970-05-23 17:21:18 America/New_York', $rendered);
+  }
+
+  /**
+   * Tests that non-chainable methods work.
+   *
+   * @covers ::__call
+   */
+  public function testChainableNonChainable() {
+    $datetime1 = new DateTimePlus('2009-10-11 12:00:00');
+    $datetime2 = new DateTimePlus('2009-10-13 12:00:00');
+    $interval = $datetime1->diff($datetime2);
+    $this->assertInstanceOf(\DateInterval::class, $interval);
+    $this->assertEquals('+2 days', $interval->format('%R%a days'));
+  }
+
+  /**
+   * Tests that chained calls to non-existent functions throw an exception.
+   *
+   * @covers ::__call
+   */
+  public function testChainableNonCallable() {
+    $this->setExpectedException(\BadMethodCallException::class, 'Call to undefined method Drupal\Component\Datetime\DateTimePlus::nonexistent()');
+    $date = new DateTimePlus('now', 'Australia/Sydney');
+    $date->setTimezone(new \DateTimeZone('America/New_York'))->nonexistent();
+  }
+
+}