Laravel 5.6 getting error “Class 'Predis\Client' not found”

I do not want to use predis in laravel project. So, I have installed phpredis in my ubuntu system, php 7.2 and apache.

I have installed redis using following commands:

sudo apt-get install redis-server
sudo apt-get install php-redis

Here is my code where I have used redis: TrendingAbstract.php

<?php

namespace App\Trends;

use App\Trends\Contracts\Trending;
use Illuminate\Support\Facades\Redis;

abstract class TrendingAbstract implements Trending
{
    /**
    * Fetch all trending resource
    *
    * @param  integer $limit
    * @return array
    */
    public function get($limit = 1)
    {
        return array_map('json_decode', Redis::zrevrange($this->cacheKey(), 0, $limit - 1));
    }

    /**
     * Reset all trending resource.
     */
    public function reset()
    {
        Redis::del($this->cacheKey());
    }
}

TrendingArticles.php

<?php

namespace App\Trends;

use App\Models\Article;
use Illuminate\Support\Facades\Redis;

class TrendingArticles extends TrendingAbstract
{
    /**
     * Get the cache key name.
     *
     * @return string
     */
    public function cacheKey()
    {
        return 'trending_article';    
    }

    /**
     * Push a new resource to the trending list.
     *
     * @param App\Models\Article $article
     */
    public function push(Article $article)
    {
        Redis::zincrby($this->cacheKey(), 1, json_encode([
            'title' => $article->title,
            'path' => $article->path
        ]));
    }
}

I did not understand what is the issue here. Same code is working fine with my another project in laravel 5.5. But not working in Laravel 5.6.

Does I am missing any configuration for phpredis? Please guide.