public function testNif()
{
$this->assertTrue(EsValidation::nif('K1254868A'));
$this->assertTrue(EsValidation::nif('K3548762H'));
$this->assertTrue(EsValidation::nif('L5876542A'));
$this->assertFalse(EsValidation::nif('X5876542A'));
$this->assertFalse(EsValidation::nif('Z2548769Y'));
$this->assertFalse(EsValidation::nif('32050031Z'));
}