Testing form data for a simple resource (Filament v3).

php 
livewire(CityResource\Pages\ManageCities::class)
        ->mountAction('create')
        //Check that all fields are required
        ->setActionData([
           'state'=>null,
            'name' => null
          ])
        ->callMountedAction()
        ->assertHasActionErrors(['state' => ['required'], 'name' => ['required'])]);