Mock request() global helper

I have a test that creates a user in Stripe. In order to do this, I am using the request() helper because of it's convenience. This is what my create method looks like to create the Stripe customer:

public function create()
    {
        return Customer::create([
            'description' => request('lastName') . ', ' . request('firstName'),
            'email' => request('email'),
            'source' => request('token'),
            'metadata' => [
                'first_name' => request('firstName'),
                'last_name' => request('lastName'),
                'address' => request('address'),
                'zip' => request('zip'),
                'phone' => request('phone'),
            ]
        ], ['api_key' => config('services.stripe.secret')]);
    }

This is not in the controller, but in its own class called StripeCustomer. This would be a unit test because it is part of a series of events that happens when a donation is posted, otherwise I would test it using $this->post()...

So, how can I mock the global request so that I can add the fields necessary to test my method?