Mocking native PHP functions (date(), time() and shell_exec) for PHPUnit using php-mock/php-mock and php-mock/php-mock-phpunit

PHPNativeFunctionMock.php

<?php
namespace Foo\Bar;

use phpmock\MockBuilder;
use phpmock\phpunit\PHPMock;
use PHPUnit_Framework_TestCase;

class Baz
{
    /**
     * @return string
     */
    public function getDate(): string
    {
        return date('Y-m-d H:i:s');
    }

    /**
     * @return int
     */
    public function getTime(): int
    {
        return time();
    }

    /**
     * @return string
     */
    public function exec(): string
    {
        return shell_exec('cmd.sh');
    }
}

class BazTest extends PHPUnit_Framework_TestCase
{
    use PHPMock;

    /**
     * @var Baz
     */
    private $baz;

    /**
     * Mocking date() and time() methods for _all_ test cases
     */
    public static function setUpBeforeClass()
    {
        parent::setUpBeforeClass();

        $builder = new MockBuilder();
        $builder->setNamespace(__NAMESPACE__);

        $builder->setName('date')
            ->setFunction(
                function() {
                    return '2016-12-30 01:00:00';
                }
            );
        $dateMock = $builder->build();
        $dateMock->enable();

        $builder->setName('time')
            ->setFunction(
                function() {
                    return strtotime('2016-12-30 01:00:00');
                }
            );
        $timeMock = $builder->build();
        $timeMock->enable();
    }

    protected function setUp()
    {
        parent::setUp();

        $this->baz = new Baz();
    }

    public function testGetDate()
    {
        $this->assertSame('2016-12-30 01:00:00', $this->baz->getDate());
    }

    public function testGetTime()
    {
        $this->assertSame(strtotime('2016-12-30 01:00:00'), $this->baz->getTime());
    }

    public function testExec()
    {
        // mocking shell_exec for selected test case using getFunctionsMock()
        $mock = $this->getFunctionMock(__NAMESPACE__, 'shell_exec');
        $mock->expects($this->once())->with('cmd.sh')->willReturn('output');

        $this->assertSame('output', $this->baz->exec());
    }
}