IOC Container Bindings are not available in Unit Test

Hi, I have bound an Interface in IOC Container using Service provider, I found it working while resolving it using tinker but when I use it in unit test it doesn't find any binding. Could someone help me to resolve this issue. Thanks in advance.

Code in service provider.

    // Private chat
        $this->app->bind(IPrivateChat::class, function ($app){
            return $this->app->makeWith(IChatService::class, ['sid'=> $this->twilioPrivatechatServiceId]);
        });

Code in service class

    public function __construct()
    {
        $this->chatServiceClient = resolve(IPrivateChat::class);
    }

Code in unit test class

        $channel = (new CreateTwilioChannelService())->execute($data);

When i dd(app()->getBindings()) in tinker i get all of my bindings along with core framework, but when i dd(app()->getBindings()) i get an empty list.

Updated:

Complete code CreateTwilioChannelService.php

<?php 
namespace App\Services\Twilio;

use App\Contracts\IPrivateChat;

class CreateTwilioChannelService
{
    protected $chatServiceClient;

    public function __construct()
    {
        $this->chatServiceClient = resolve(IPrivateChat::class);
    }


    public function execute($data)
    {
        
    }
}

IPrivateChat.php

<?php 
namespace App\Contracts;

interface IPrivateChat{

}

IChatService.php

<?php
namespace  App\Contracts;

class IChatService{

    public function channels(){}

    public function users(){}
}

TwilioServiceProvider.php

<?php

namespace App\Providers;

use App\Contracts\IChatService;
use App\Contracts\IPrivateChat;
use Illuminate\Support\ServiceProvider;
use Twilio\Rest\Client;

class TwilioServiceProvider extends ServiceProvider
{
    protected $twilioAccountSid;
    protected $twilioAuthToken;
    protected $twilioApiKey;
    protected $twilioApiSecret;
    protected $twilioWatercoolerServiceId;
    protected $twilioPrivatechatServiceId;


    public function __construct($app)
    {
        $this->twilioAccountSid = config('twilio')['accountSid'];;
        $this->twilioAuthToken = config('twilio.authToken');
        $this->twilioApiKey = config('twilio')['apiKey'];
        $this->twilioApiSecret = config('twilio')['apiSecret'];
        $this->twilioWatercoolerServiceId = config('twilio.watercoolder.chatServiceSid');
        $this->twilioPrivatechatServiceId = config('twilio.privatechat.chatServiceSid');
        parent::__construct($app);
    }
    /**
     * Register services.
     *
     * @return void
     */
    public function register()
    {

        // Twilio client binding
        $this->app->bind(Client::class, function($app){
            return  new Client($this->twilioAccountSid, $this->twilioAuthToken);
        });

        $this->app->bind(IChatService::class, function($app, $params){
            return $this->app->make(Client::class)->chat->v2->services($params['sid']);
        });

        // Private chat
        $this->app->bind(IPrivateChat::class, function ($app){
            return $this->app->makeWith(IChatService::class, ['sid'=> $this->twilioPrivatechatServiceId]);
        });

    }

    /**
     * Bootstrap services.
     *
     * @return void
     */
    public function boot()
    {
        //
    }
}

CreateTwilioChannelServiceTest.php

<?php

namespace Tests\Unit\Services\Twilio;

use App\Contracts\IPrivateChat;
use App\Services\Twilio\CreateTwilioChannelService;
use PHPUnit\Framework\TestCase;

class CreateTwilioChannelServiceTest extends TestCase
{
    /**
     * A basic unit test example.
     *
     * @return void
     */
    public function testCreateTwilioChannel()
    {

        $data = [];

        // dd(app(IPrivateChat::class));
        $channel = (new CreateTwilioChannelService())->execute($data);
        
        // dd($channel);

    }
}