Test Error - Call to a member function getId() on null

it('can render product category page', function () {

    $this
        ->actingAs(user())
        ->get(ProductCategoryResource::getUrl())
        ->assertSuccessful();
});

it('can render product category page', function () {

    $this
        ->actingAs(user())
        ->get(ProductCategoryResource::getUrl())
        ->assertSuccessful();
});

it('can render product category page', function () {

    $this
        ->actingAs(user())
        ->get(ProductCategoryResource::getUrl())
        ->assertSuccessful();
});

it('can render product category page', function () {

    $this
        ->actingAs(user())
        ->get(ProductCategoryResource::getUrl())
        ->assertSuccessful();
});

The test fails because, it is not able to find current panel.
How can I pass panel in the test.
If I have more than one panel, how can I test my resources for separate panels. ?
Kindly help.