Laravel - Mock function in model

Question

In my application, I have a service that uses a function related to a model.

This function has already been tested (on its Unit Test), and in my Feature test, I just need to "use" its output value.

Because this function is "complicated", I would mock its value without warry about what the function does. This is the scenario:

Model

class MyModel
{
    public function calculateSomething()
    {
        // Implementation, already unit tested
        // Here i put some "crazy" logic (this is not real :) )
        if ($this->field_a < 10 || $this->field_b > 15) {
          return true;
        }

        if ($this->field_c !== null || $this->field_e < 50) {
           return false;
        }

        return true;
    }
}

In my Service i dont need to re-create those conditions, i just need to say "in this test calculateSomething will return true", dont care why it return true

Service

class MyService
{
    public function myMethod($id)
    {
        $models = MyModel::all();

        foreach($models as $model) {
            if ($model->calculateSomething()) {
                // Do domething here
            } else {
                // Do other stuff here
            }
        }
    }

    public function myMethodIsolated($model)
    {
        if ($model->calculateSomething()) {
            // Do domething here
        } else {
            // Do other stuff here
        }
    }
}

Usually, I mock service, but I never mock a function inside a model, it's possible to mock the function calculateSomething ?

In my example, I provided an isolated version of the function, called myMethodIsolated where I pass the single instance.