ENGCOM-7224: Fixed tests for Magento\Framework\Stdlib\DateTime\DateTime #27492

 - Merge Pull Request #27492 from andrewbess/magento2:bugfix/fix-test-for-datetime
 - Merged commits:
   1. b20f9eb
   2. 7ee81db

Author: magento-engcom-team

lib/internal/Magento/Framework/Stdlib/Test/Unit/DateTime/DateTimeTest.php

@@ -5,26 +5,33 @@
  */
 namespace Magento\Framework\Stdlib\Test\Unit\DateTime;
 
+use DateTimeImmutable;
+use DateTimeInterface;
+use Exception;
 use Magento\Framework\Stdlib\DateTime\DateTime;
 use Magento\Framework\Stdlib\DateTime\TimezoneInterface;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
 
 /**
- * Magento\Framework\Stdlib\DateTimeTest test case
+ * Tests for @see DateTime
  */
-class DateTimeTest extends \PHPUnit\Framework\TestCase
+class DateTimeTest extends TestCase
 {
     /**
      * @var string
      */
     private $testDate = '2015-04-02 21:03:00';
 
     /**
-     * @param int|string|\DateTimeInterface $input
+     * @param int|string|DateTimeInterface $input
+     * @throws Exception
+     *
      * @dataProvider dateTimeInputDataProvider
      */
     public function testGmtTimestamp($input)
     {
-        /** @var TimezoneInterface|\PHPUnit_Framework_MockObject_MockObject $timezone */
+        /** @var TimezoneInterface|MockObject $timezone */
         $timezone = $this->getMockBuilder(TimezoneInterface::class)->getMock();
         $timezone->method('date')->willReturn(new \DateTime($this->testDate));
 
@@ -33,12 +40,14 @@ public function testGmtTimestamp($input)
     }
 
     /**
-     * @param int|string|\DateTimeInterface $input
+     * @param int|string|DateTimeInterface $input
+     * @throws Exception
+     *
      * @dataProvider dateTimeInputDataProvider
      */
     public function testTimestamp($input)
     {
-        /** @var TimezoneInterface|\PHPUnit_Framework_MockObject_MockObject $timezone */
+        /** @var TimezoneInterface|MockObject $timezone */
         $timezone = $this->getMockBuilder(TimezoneInterface::class)->getMock();
         $timezone->method('date')->willReturn(new \DateTime($this->testDate));
 
@@ -48,29 +57,50 @@ public function testTimestamp($input)
 
     public function testGtmOffset()
     {
-        /** @var TimezoneInterface|\PHPUnit_Framework_MockObject_MockObject $timezone */
+        /** @var TimezoneInterface|MockObject $timezone */
         $timezone = $this->getMockBuilder(TimezoneInterface::class)->getMock();
-        // Asia/Tbilisi timezone have no DST
-        $timezone->method('getConfigTimezone')->willReturn('Asia/Tbilisi');
+        $timezone->method('getConfigTimezone')->willReturn('Europe/Amsterdam');
 
-        /** @var DateTime|\PHPUnit_Framework_MockObject_MockObject $dateTime */
+        /** @var DateTime|MockObject $dateTime */
         $dateTime = $this->getMockBuilder(DateTime::class)
             ->setConstructorArgs([$timezone])
             ->setMethods(null)
             ->getMock();
 
-        $this->assertEquals(14400, $dateTime->getGmtOffset());
+        $this->assertEquals(
+            $this->getExpectedGtmOffset($timezone->getConfigTimezone()),
+            $dateTime->getGmtOffset()
+        );
     }
 
     /**
+     * Returns expected offset according to Daylight Saving Time in timezone
+     *
+     * @param string $timezoneIdentifier
+     * @return int
+     */
+    private function getExpectedGtmOffset(string $timezoneIdentifier): int
+    {
+        $timeZoneToReturn = date_default_timezone_get();
+        date_default_timezone_set($timezoneIdentifier);
+        $expectedOffset = (date('I', time()) + 1) * 3600;
+        date_default_timezone_set($timeZoneToReturn);
+
+        return (int) $expectedOffset;
+    }
+
+    /**
+     * Data provider
+     *
      * @return array
+     * @throws Exception
      */
     public function dateTimeInputDataProvider()
     {
         return [
             'string' => [$this->testDate],
             'int' => [strtotime($this->testDate)],
-            \DateTimeInterface::class => [new \DateTimeImmutable($this->testDate)],
+            DateTimeInterface::class => [new DateTimeImmutable($this->testDate)],
         ];
     }
 }