Is Fibonacci?

FibonacciValidator.php

<?php

class FibonacciValidator
{
    public function isFibonacci($number)
    {
        $positiveVerification = (5 * pow($number, 2) + 4);
        $negativeVerification = (5 * pow($number, 2) - 4);
        
        return ($positiveVerification % 4 == 0 || $negativeVerification % 4 == 0);
    }
}

FibonacciValidatorTest.php

<?php

class FibonacciValidatorTest extends \PHPUnit_Framework_TestCase
{
    private $validator = null;
    
    protected function setUp()
    {
        $this->validator = new FibonacciValidator;
    }
    
    protected function tearDown()
    {
        $this->validator = null;
    }
    /**
     * @dataProvider validNumbersDataProvider 
     */
    public function testShouldReturnTrueWhenNumberIsInSequence($validNumber)
    {
        $this->assertTrue($this->validator->isFibonacciNumber($validNumber));
    }
    
    /**
     * @dataProvider invalidNumbersDataProvider 
     */
    public function testShouldReturnFalseWhenNumberIsNotInSequence()
    {
        $this->assertFalse($this->validator->isFibonacciNumber($validNumber));
    }
    
    public function validNumbersDataProvider()
    {
        return array(1, 1, 2, 3, 5, 8, 13);
    }
    
    public function invalidNumbersDataProvider()
    {
        return array(4, 7, 12);
    }
}