Testbench: Error: Class "App\Models\User" not found

After a few years hiatus from Laravel, I'm finally getting around to learning how to create packages and perform unit tests.

My first package is a very simple one: a user can block another user. The package works great, but when trying to write my first test I get the error: Error: Class "App\Models\User" not found, even though it's clearly imported.

Even if I inline it instead of using a factory it still throws that error.

// this also throws an error
\App\Models\User::create(['John', '[email protected]','12345678']);

Here's my test

<?php

namespace TimGavin\LaravelBlock\Tests;

use App\Models\User;
use Illuminate\Foundation\Testing\DatabaseMigrations;
use Orchestra\Testbench\TestCase;

class BlockTest extends TestCase
{
    use DatabaseMigrations;

    /** @test */
    public function a_user_can_block_another_user()
    {
        $userA = User::factory()->create();
        $userB = User::factory()->create();

        $userA->block($userB);
    }
}

Here's the error

1) TimGavin\LaravelBlock\Tests\BlockTest::a_user_can_block_another_user
Error: Class "App\Models\User" not found

If I remove the user inserts and block check, and just replace with $this->assertTrue(true); the test passes. So weird.

What am I doing wrong?