How to test a server action function?

Question

I have a nextjs server action that uses mssql for node to connect with the database.

The following is pizza.actions.ts:

export async function get_pizza_id(pizza_name: string) {
    try {
        if(!pool.connected) {
            await connectDB();
        }

        const result = await pool.request()
            .input('pizza_name', pizza_name)
            .query('SELECT pizza_id FROM phut.pizza WHERE pizza_name = @pizza_name');

        return result.recordset;
    } 
    catch (error) {
        console.error('Error fetching pizza:', error);
        throw error;
    }
}

After creating this script - I wanted to write a test to ensure that it works - such that whenever I make code changes in the future I can test whether all functionalities are working.

The docs recommend using E2E testing.

While I have some experience using selenium, they recommend playwright. I am looking for recommended way to develop web-app systems that are full-stack and use next.js or similar frameworks.

Note: I understand that there is no specific answer for this - and some stackoverflow users have issues answering such questions. I am hoping the community is stronger and that it can guide me - specially since I truly believe design and testing are fundamental for efficient software development. I am attempting to avoid potential pitfalls by asking this here.

I tried using jest for testing the api links but it wasn't picking up environment variables - and while attempting to solve the issue realized that I might be using the tool wrong

import dotenv from 'dotenv';
dotenv.config({ path: '.env.test.local' });

describe('updatePizza', () => {
    it('should update the user details if the pizza exists', async () => {
        // Mock the database connection and request methods
        
        const params = {
            id: 1,
            pizza_name: 'Sid',
            pizza_price:23,
        };

        if(!pool.connected) {
            connectDB();
        }
        const result = await updatePizza(params);

        expect(result.rowsAffected).toEqual([1]);
    });