public function testMultiplication(array $polynomialA, array $polynomialB, array $expected_product)
{
$polynomialA = new Polynomial($polynomialA);
$polynomialB = new Polynomial($polynomialB);
$expected = new Polynomial($expected_product);
$product = $polynomialA->multiply($polynomialB);
$this->assertEquals($expected, $product);
}