Pop\Db\Sql::factory PHP Method

    public static function factory(Db $db, $table = null, $alias = null)
    {
        return new self($db, $table, $alias);
    }

 public function testIsNotNull()
 {
     $p = new Predicate(Sql::factory(Db::factory('Sqlite', array('database' => __DIR__ . '/../tmp/test.sqlite')), 'users'));
     $p->isNotNull('email');
     $this->assertEquals('("email" IS NOT NULL)', (string) $p);
 }