How do I set up Prismock with Jest for unit testing?

Create a __mocks__ directory at your project root with an @prisma/client.js file that exports PrismockClient as PrismaClient, or use jest.mock to replace PrismaClient in your test setup. This enables automatic mocking across all tests without a live database.

What are the main differences between Prismock and real Prisma for testing?

Prismock runs in-memory without a database, making tests faster and isolated, but it doesn't support all Prisma features like JSON filters. Real Prisma requires a live database and offers full feature coverage, which is better for integration testing but slower.

Does Prismock support MongoDB-specific queries?

Yes, Prismock is tested against MongoDB and supports most queries, but custom MongoDB methods like $runCommandRaw are not yet implemented, as noted in the roadmap. Basic CRUD operations and relationships work as expected.

How to handle decimal fields with Prismock?

Prismock has dedicated documentation for use with decimal.js, requiring additional setup to mock decimal types correctly. Refer to the 'use with decimal.js' link in the README for specific instructions on integrating decimal.js.

Can I use Prismock for integration testing instead of unit testing?

Prismock is designed for unit testing where database isolation is key. For integration testing that requires real database interactions, transactions, or persistent data, it's not ideal due to its in-memory nature and missing features.

Prismock or prisma-mock: which should I use?

Prismock is schema-aware and extensively tested against real Prisma, making it more accurate for complex projects with relationships. prisma-mock is simpler but may lack feature depth. Choose Prismock for reliability in unit tests, but verify unsupported features for your use case.

Open-Awesome

Prismock - Run tests in isolation with an in-memory implementation of Prisma

MITTypeScriptv1.35.4

A mock for PrismaClient that reads your Prisma schema and provides an in-memory store for fast, isolated unit tests.

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What is Prismock - Run tests in isolation with an in-memory implementation of Prisma?

Prismock is a mocking library for PrismaClient that reads your Prisma schema and provides an in-memory implementation for unit testing. It simulates Prisma's API to allow developers to write fast, isolated tests without needing a live database connection. The library is extensively tested against real Prisma results to ensure accuracy across MySQL, PostgreSQL, and MongoDB environments.

Target Audience

Developers using Prisma ORM who need to write unit tests for their applications without relying on a live database. It is particularly useful for backend engineers, full-stack developers, and educators teaching testing practices with Prisma.

Value Proposition

Prismock offers a schema-aware, in-memory mock that closely replicates Prisma's behavior, enabling reliable and fast unit tests. Unlike generic mocks, it reads your actual Prisma schema, supports most Prisma features, and is validated against real database results, reducing test flakiness and integration complexity.

Overview

A mock for PrismaClient, dedicated to unit testing.

Use Cases

Best For

Unit testing Prisma-based applications without a live database
Creating isolated test environments for CI/CD pipelines
Testing Prisma queries and relationships in memory
Educational purposes for teaching backend testing with Prisma
Prototyping applications with an in-memory Prisma implementation
Ensuring test retry-ability by avoiding external database dependencies

Not Ideal For

Applications relying heavily on JSON field queries or scalar list filters
Integration testing requiring real database transactions and persistence
Production use cases where data must survive beyond in-memory sessions

Pros & Cons

Pros

Schema-Aware Accuracy

Reads your actual Prisma schema to generate models and relationships, ensuring the mock closely mirrors your database structure for reliable testing.

Comprehensive API Simulation

Supports most Prisma query methods, filters, and nested operations, with validation against real Prisma results across MySQL, PostgreSQL, and MongoDB.

Easy Test Integration

Offers seamless setup with Jest and ViTest via automatic mocking or manual instantiation, fitting smoothly into existing testing workflows.

Fast In-Memory Execution

Stores data in-memory for rapid, isolated test runs without external database dependencies, ideal for CI/CD pipelines and retry-able tests.

Cross-Environment Validation

Tested against real Prisma outcomes for multiple databases, increasing confidence in mock reliability and reducing test flakiness.

Cons

Incomplete Feature Coverage

Lacks support for key Prisma features like JSON filters, scalar list methods, and some nested operations (e.g., set, disconnect), which can break tests for complex schemas.

Setup Complexity for Custom Paths

Requires additional configuration via createPrismock for custom Prisma client output paths, adding overhead compared to standard setups.

Partial Advanced Query Support

GroupBy queries have limitations such as no skip, take, or cursor support, and referential actions like onUpdate are unsupported, restricting certain testing scenarios.

Potential Behavioral Gaps

As a mock, it may not perfectly replicate all edge cases of real Prisma behavior, necessitating manual verification for critical or unsupported queries.

Frequently Asked Questions

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