Prisma Mock

A comprehensive mock of the Prisma API intended for unit testing. All data is stored in memory, providing fast and reliable test execution without external dependencies.

The library uses jest-mock-extended or vitest-mock-extended, which means that if functionality you need is not implemented yet, you can mock it yourself.

Installation

npm install prisma-mock --save-dev
# or
yarn add prisma-mock --dev

Usage

Basic Example

Simple example of how to create a prisma mock instance:

import createPrismaMock from "prisma-mock"

let client

beforeEach(() => {
  client = createPrismaMock()
})

Mocking Global Prisma Instance

Example of how to mock a global prisma instance, as the default export in a "db" directory (like BlitzJS):

import createPrismaMock from "prisma-mock"
import { mockDeep, mockReset } from "jest-mock-extended"

jest.mock("db", () => ({
  __esModule: true,
  ...jest.requireActual("db"),
  default: mockDeep(),
}))

import db, { Prisma } from "db"

beforeEach(() => {
  mockReset(db)
  createPrismaMock({}, Prisma.dmmf.datamodel)
})

With Initial Data

You can optionally start with pre-filled data:

const client = createPrismaMock({
  user: [
    {
      id: 1,
      name: "John Doe",
      accountId: 1,
    },
  ],
  account: [
    {
      id: 1,
      name: "Company",
    },
  ],
})

API

createPrismaMock(
  data: PrismaMockData<P> = {},
  datamodel?: Prisma.DMMF.Datamodel,
  client = mockDeep<P>(),
  options: {
    caseInsensitive?: boolean
    enableIndexes?: boolean
  } = {}
): Promise<P>

Parameters

data (optional)

Initial mock data for the Prisma models. An object containing keys for tables and values as arrays of objects.

datamodel (optional)

The Prisma datamodel, typically Prisma.dmmf.datamodel. Defaults to the current Prisma client's datamodel.

client (optional)

A jest-mock-extended instance. If not provided, a new instance is created.

options (optional)

Configuration options for the mock client:

• caseInsensitive (boolean, default: false): If true, all string comparisons are case insensitive
• enableIndexes (boolean, default: false) Experimental: If true, enables indexing for better query performance on primary keys, unique fields, and foreign keys

Return Value

Returns a mock Prisma client with all standard model methods plus:

• $getInternalState(): Method to access the internal data state for testing/debugging

Supported Features

Model Queries ✅

• findUnique / findUniqueOrThrow
• findMany
• findFirst / findFirstOrThrow
• create
• createMany
• delete
• update
• deleteMany
• updateMany
• upsert
• count
• aggregate

Model Query Options ✅

• distinct
• include
• where
• select
• orderBy
• select: _count

Nested Queries ✅

• create
• createMany
• update
• updateMany
• delete
• deleteMany
• connect
• disconnect
• set
• upsert

Filter Conditions and Operators ✅

• equals
• gt, gte, lt, lte
• not
• in, notIn
• contains, startsWith, endsWith
• AND, OR, NOT
• mode (for case-insensitive matching)

Relation Filters ✅

• some
• every
• none

Atomic Number Operations ✅

• increment
• decrement
• multiply
• divide
• set

JSON Filters ✅

• path
• string_contains
• string_starts_with
• string_ends_with
• array_contains
• array_starts_with
• array_ends_with

Attributes ✅

• @@id (Primary keys)
• @default (Default values)
• @unique (Unique constraints)
• @@unique (Compound unique constraints)
• @relation (Relationships)
• @updatedAt (Partially supported - set at creation)

Attribute Functions ✅

• autoincrement()
• cuid()
• uuid()
• now()

Referential Actions ✅

• onDelete: SetNull
• onDelete: Cascade

Prisma Client Methods ✅

• $transaction (Array of promises)
• $transaction (Interactive transactions with rollback)
• $connect
• $disconnect

Not Yet Implemented

The following features are planned but not yet implemented:

Model Queries

• groupBy

Nested Queries

• connectOrCreate

Filter Conditions

• search (Full-text search)

Relation Filters

• is

Scalar List Methods

• set
• push

Scalar List Filters

• has
• hasEvery
• hasSome
• isEmpty
• equals

Attributes

• auto()
• dbgenerated()

Referential Actions

• onDelete: Restrict
• onDelete: NoAction
• onDelete: SetDefault
• onUpdate actions

Prisma Client Methods

• $transaction (Isolation levels)
• $use (Middleware)

Performance Features

Indexing (Experimental)

Enable indexing for better query performance:

const client = createPrismaMock({}, undefined, undefined, {
  enableIndexes: true,
})

When enabled, indexes are automatically created for:

• Primary key fields
• Unique fields
• Foreign key fields

This can significantly improve query performance for large datasets.

Error Handling

The mock client throws appropriate Prisma errors with correct error codes:

• P2025: Record not found (for findUniqueOrThrow, findFirstOrThrow)
• P2002: Unique constraint violation
• P2003: Foreign key constraint violation

Testing

Writing Tests

Create your tests in the __tests__ directory. You can use snapshot testing with either expect(res).toMatchSnapshot() or expect(res).toMatchInlineSnapshot().

Note: If you choose to use snapshot testing, make sure to first run your tests against the real database to create a snapshot of the expected result.

Running Tests

To run tests against a PostgreSQL database:

yarn run test:postgres

To run tests against prisma-mock (in-memory database):

yarn test

Development

Requirements

Create a .env-cmdrc file in the root of your project with the following content:

{
  "postgres": {
    "PROVIDER": "postgresql",
    "DATABASE_URL": "postgresql://postgres:postgres@localhost:5432/postgres?schema=public"
  }
}

Building

yarn build

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

License

MIT