Testing trait with PHPUnit

namespace Inanzzz\ApplicationBundle\Util;

trait CalculatorUtil
{
    public function sum($a, $b)
    {
        return $a+$b;
    }

    public function sub($a, $b)
    {
        if ($a == 0) {
            return;
        }

        return $a-$b;
    }
}

namespace tests\Inanzzz\ApplicationBundle\Util;

use Inanzzz\ApplicationBundle\Util\CalculatorUtil;
use PHPUnit\Framework\TestCase;
use PHPUnit_Framework_MockObject_MockObject;

class CalculatorUtilTest extends TestCase
{
    /** @var CalculatorUtil|PHPUnit_Framework_MockObject_MockObject */
    private $calculatorTraitMock;

    protected function setUp()
    {
        $this->calculatorTraitMock = $this->getMockForTrait(CalculatorUtil::class);
    }

    protected function tearDown()
    {
        $this->calculatorTraitMock = null;
    }

    public function testSum()
    {
        $this->assertEquals(3, $this->calculatorTraitMock->sum(1, 2));
    }

    public function testSub()
    {
        $this->assertEquals(3, $this->calculatorTraitMock->sub(5, 2));
        $this->assertEquals(-1, $this->calculatorTraitMock->sub(1, 2));

        $this->assertEquals(-3, $this->calculatorTraitMock->sub(-1, 2));
        $this->assertEquals(-3, $this->calculatorTraitMock->sub(-2, 1));

        $this->assertEquals(3, $this->calculatorTraitMock->sub(1, -2));
        $this->assertEquals(3, $this->calculatorTraitMock->sub(2, -1));

        $this->assertEquals(1, $this->calculatorTraitMock->sub(-1, -2));
        $this->assertEquals(-1, $this->calculatorTraitMock->sub(-2, -1));

        $this->assertEquals(0, $this->calculatorTraitMock->sub(-2, -2));

        $this->assertEquals(1, $this->calculatorTraitMock->sub(1, 0));

        $this->assertNull($this->calculatorTraitMock->sub(-0, 2));
        $this->assertNull($this->calculatorTraitMock->sub(0, 2));
    }
}

$ vendor/bin/phpunit
PHPUnit 4.8.36 by Sebastian Bergmann and contributors.

..

Time: 199 ms, Memory: 4.00MB

OK (2 tests, 13 assertions)