PhpUnit and Laravel 5.4 how to mock Session data during a test

I'm testing a class in laravel 5.4 with phpunit that uses the session to get data. Retrieving the session data works when accessing it directly when the app is running aka "session('consumer')" returns a value, however when i try to test a function that uses the session, I get the below error:

ReflectionException: Class session does not exist

Can someone please shed some light on how to accomplish setting session data during a test.

I have tried using:

$this->session()->put([$array_value]) but get an error "class session does not exist on class_im_testing"

Thanks in advance for your help!

public function test_get_user()
{
    $mockUser =  [
        'id' => 'cf442564-d076-4198-beb5-edef5aa51a69',
        'name' => 'John Doe',
        'fname' => 'John',
        'lname' => 'Doe',  
    ];

    session->put('consumer', [
        'id' => 'cf442564-d076-4198-beb5-edef5aa51a69',
        'name' => 'John Doe',
        'fname' => 'John',
        'lname' => 'Doe',  
    ]);

    $user = $this->repo->getUser();

    $this->assertEqual($user, $mockUser);
}

public function getUser()
{
   $user = new User(session('consumer'));
   return $user;
}