How To Unit Test NextJS API Route That Uses Repository Pattern?

I am new prisma / nextjs user and I am trying to understand how to unit test an API route that uses prisma. I have read the unit testing guide.

I like the dependency injection approach and have started trying to implement it. However I am struggling with the following development issue. Can anybody help?

• With the dependency injection approach the unit testing guide explains how to setup the mock context and use this in the data access layer. Does anyone have any examples of how and where the real context could be initialised and used with an API route that uses a repository pattern? Is it possible to expand the next.js api handler with middleware to include the context to facilitate testing?

import type { NextApiRequest, NextApiResponse } from 'next'

import { PublishRepository } from '../../../repository'

// PUT /api/publish/:id
export default async function handle(
    req: NextApiRequest,
    res: NextApiResponse
) {
    if (req.method == 'PUT') {
        const postId = req.query.id;


        let repo = new PublishRepository( // where does the live context come from and how is it initialised??? )
        const post = repo.set_published(postId)

        res.json(post);
    }
}

Repository - Initialised using Context instance - How is this initialise for development and how is it mocked?

import { Post, PrismaClient } from "@prisma/client"
import { Context } from "../context"

import prisma from "lib/prisma"


export class PublishRepository {
    private prisma: PrismaClient

    constructor(context: Context) {
        this.prisma = context.prisma
    }

    async set_published(post_id: string | string[]): Promise<Post> {
        return await prisma.post.update({
            where: { id: Number(post_id) },
            data: { published: true },
        });
    }
}