prismock

This is a mock for PrismaClient. It actually reads your schema.prisma and generate models based on it.

It perfectly simulates Prisma's API and store everything in-memory for fast, isolated, and retry-able unit tests.

It's heavily tested, by comparing the mocked query results with real results from prisma. Tested environments include MySQL, PostgreSQL and MongoDB.

This library can also be used as an in-memory implementation of Prisma, for reasons such as prototyping, but that's not its primary goal.

Installation

After setting up Prisma:

yarn

$ yarn add -D prismock

npm

$ npm add --save-dev prismock

Usage

There is two options here, depending on your application architecture.

PrismaClient

You can mock the PrismaClient directly (Example):

import { PrismaClient } from '@prisma/client';
import { generatePrismock } from 'prismock';

jest.mock('@prisma/client', () => {
  return {
    ...jest.requireActual('@prisma/client'),
    PrismaClient: jest.fn(),
  };
});

beforeAll(async () => {
  const prismock = await generatePrismock();
  (PrismaClient as jest.Mock).mockReturnValue(prismock);
});

Dependency injection

If you are using dependency injection, you can directly use prismock. I personally do so with the amazing NestJS:

import { generatePrismock } from 'prismock';

let app: INestApplication;

beforeAll(async () => {
  const prismock = await generatePrismock();

  const moduleRef = await Test.createTestingModule({ imports: [] })
    .overrideProvider(PrismaService)
    .useValue(prismock)
    .compile();

  app = moduleRef.createNestApplication();
  await app.init();
});

Then, you will be able to write your tests as if your app was using an in-memory Prisma client.

Alternative Synchronous Client Generation

You may have the option to generate the Prismock client synchronously if you have access to the DMMF (Datamodel Meta Format).

import { generatePrismockSync } from 'prismock';
import { Prisma } from '__generated__/client';

const models = Prisma.dmmf.datamodel.models;
const prismock = generatePrismockSync({ models });

API

generatePrismock

generatePrismock(
  pathToSchema?: string,
): Promise<PrismaClient>

The returned object is similar to a PrismaClient, which can be used as-is.

pathToSchema

Path to the schema file. If not provided, the schema is prisma/schema.prisma.

generatePrismockSync

generatePrismockSync(
  models?: DMMF.Model[],
): PrismaClient

The returned object is similar to a PrismaClient, which can be used as-is.

models

List of models extracted from the DMMF document.

Internal data

Two additional functions are returned with the PrismaClient, getData and setData. In some edge-case, we need to directly access, or change, the data store management by prismock.

Most of the time, you won't need it in your test, but keep in mind they exist

const prismock = await generatePrismock();
prismock.setData({ user: [] });

const prismock = await generatePrismock();
prismock.getData(); // { user: [] }

Supported features

Model queries

Feature	State
findUnique	✔
findFirst	✔
findMany	✔
create	✔
createMany	✔
delete	✔
deleteMany	✔
update	✔
updateMany	✔
upsert	✔
count	✔
aggregate	✔
groupBy	⛔

Model query options

Feature	State
distinct	✔
include	✔
where	✔
select	✔
orderBy	⛔
select + count	⛔

Nested queries

Feature	State
create	✔
createMany	✔
update	✔
updateMany	✔
connect	✔
connectOrCreate	✔
set	⛔
disconnect	⛔
upsert	⛔
delete	⛔

Filter conditions and operators

Feature	State
equals	✔
gt	✔
gte	✔
lt	✔
lte	✔
not	✔
in	✔
notIn	✔
contains	✔
startWith	✔
endsWith	✔
AND	✔
OR	✔
NOT	✔
mode	✔
search	⛔

Relation filters

Feature	State
some	✔
every	✔
none	✔
is	⛔

Scalar list methods

Feature	State
set	⛔
push	⛔

Scalar list filters

Feature	State
has	⛔
hasEvery	⛔
hasSome	⛔
isEmpty	⛔
equals	⛔

Atomic number operations

Feature	State
increment	✔
decrement	✔
multiply	✔
divide	✔
set	✔

JSON filters

Feature	State
path	⛔
string_contains	⛔
string_starts_withn	⛔
string_ends_with	⛔
array_contains	⛔
array_starts_with	⛔
array_ends_with	⛔

Attributes

Feature	State
@@id	✔
@default	✔
@relation	✔
@unique	⛔
@@unique	⛔
@updatedAt	⛔

Attribute functions

Feature	State
autoincrement()	✔
now()	✔
uuid()	✔
auto()	⛔
cuid()	⛔
dbgenerated	⛔

Referential actions

Feature	State
onDelete (SetNull, Cascade)	✔
onDelete (Restrict, NoAction, SetDefault)()	⛔
onUpdate	⛔

Roadmap

• Complete supported features.
• Refactoring of update operation.
• Replace item formating with function composition
• Restore test on _count for mongodb
• Add custom client method for MongoDB ($runCommandRaw, findRaw, aggregateRaw)

Motivation

While Prisma is amazing, its unit testing section is treated as optional. On the other hand, it should be a priority for developers to write tests.

As I love Prisma, I decided to create this package, in order to keep using it on real-world projects.

I'm also a teacher and believe it's mandatory for students to learn about testing. I needed a similar solution for my backend course, so I created my own.

Feature request

I'm personally using this library in my day-to-day activities, and add features or fix bugs depending on my needs.

If you need unsupported features or discover unwanted behaviors, feel free to open an issue, I'll take care of it.

Credit

Inspired by prisma-mock.