TimerTest.php

<?php

namespace Drupal\Tests\Component\Utility;

use Drupal\Component\Utility\Timer;
use PHPUnit\Framework\TestCase;

/**
 * Tests the Timer system.
 *
 * @group Utility
 *
 * @coversDefaultClass \Drupal\Component\Utility\Timer
 */
class TimerTest extends TestCase {
    
    /**
     * Tests Timer::read() time accumulation accuracy across multiple restarts.
     *
     * @covers ::start
     * @covers ::stop
     * @covers ::read
     */
    public function testTimer() {
        Timer::start('test');
        usleep(5000);
        $value = Timer::read('test');
        usleep(5000);
        $value2 = Timer::read('test');
        usleep(5000);
        $value3 = Timer::read('test');
        usleep(5000);
        $value4 = Timer::read('test');
        // Although we sleep for 5 milliseconds, we should test that at least 4 ms
        // have past because usleep() is not reliable on Windows. See
        // http://php.net/manual/function.usleep.php for more information. The
        // purpose of the test to validate that the Timer class can measure elapsed
        // time not the granularity of usleep() on a particular OS.
        $this->assertGreaterThanOrEqual(4, $value, 'Timer failed to measure at least 4 milliseconds of sleeping while running.');
        $this->assertGreaterThanOrEqual($value + 4, $value2, 'Timer failed to measure at least 8 milliseconds of sleeping while running.');
        $this->assertGreaterThanOrEqual($value2 + 4, $value3, 'Timer failed to measure at least 12 milliseconds of sleeping while running.');
        $this->assertGreaterThanOrEqual($value3 + 4, $value4, 'Timer failed to measure at least 16 milliseconds of sleeping while running.');
        // Stop the timer.
        $value5 = Timer::stop('test');
        $this->assertGreaterThanOrEqual($value4, $value5['time'], 'Timer measured after stopping was not greater than last measurement.');
        // Read again.
        $value6 = Timer::read('test');
        $this->assertEquals($value5['time'], $value6, 'Timer measured after stopping was not equal to the stopped time.');
        // Restart.
        Timer::start('test');
        usleep(5000);
        $value7 = Timer::read('test');
        $this->assertGreaterThanOrEqual($value6 + 4, $value7, 'Timer failed to measure at least 16 milliseconds of sleeping while running.');
        // Stop again.
        $value8 = Timer::stop('test');
        $value9 = Timer::read('test');
        $this->assertEquals($value8['time'], $value9, 'Timer measured after stopping not equal to stop time.');
    }

}