refactor code to be database-agnostic

Actually I have two questions:

1) Is it possible to configure Laravel temporarily for a call to be database-agnostic and work on models instantiated in code only? In other words to prevent any database access when working with models and relations.

2) I tried to refactor this code to allow 1 but I'm hitting problems

/** @var Collection $collection */
    $collection = $model->relation()->whereIn('MY_ID', [
        RelationModel::IDENTIFIER_FOO,
        RelationModel::IDENTIFIER_BAR,
        // ...
    ])->get();
    if (0 === $collection->count()) {
        throw new \InvalidArgumentException('no entry found but mandatory');
}

Which I tried to change to this:

/** @var Collection $collection */
    // note the missing parentheses
    $collection = $model->relation->whereIn('MY_ID', [
        RelationModel::IDENTIFIER_FOO,
        RelationModel::IDENTIFIER_BAR,
        // ...
    ])->get();
    if (0 === $collection->count()) {
        throw new \InvalidArgumentException('no entry found but mandatory');
}

But now I'm getting the error

Type error: Too few arguments to function Illuminate\Support\Collection::get(), 0 passed

It seems omitting the parentheses there is a different type of collection returned which requires to pass a parameter instead of none for the other type of collection.

Is it possible to refactor this to allow both kinds of requests, with and without database access?

via Chebli Mohamed