How do I prevent my Prisma mock from creating entries in the database

I am trying to unit test my database based on the Prisma unit testing documentation. When I run my tests though, calls are actually going out to the database. I was under the impression mocking the Prisma client would prevent that.

I wrote code to initialize the Prisma client.

import { PrismaClient } from "@prisma/client"

let prisma

if(process.env.NODE_ENV === 'production') {
    prisma = new PrismaClient()
} else {
    if(!global.prisma) {
        global.prisma = new PrismaClient()
    }
    prisma = global.prisma
}

export default prisma

I wrote code to create an entry in the database.

export async function createTest(id) {
    const result = await await prisma.test.create({
        data: {
            id: id,
        },
    })

    return result
}

And I wrote code to test the create function.

import { createTest } from '../lib/crud'
import { prismaMock } from '../lib/mock/singleton'

it('confirms an entry can be created in the database', async () => {
    const id = 1

    prismaMock.test.create.mockResolvedValue(id)

    await expect(createTest(id)).resolves.toEqual({
        id: 1,
    })
})

Am I missing something? Why is the create function actually creating entries in the database when the tests run?