---
title: "The Ultimate Guide to Testing with Prisma: Unit Testing"
url: https://daily.dev/posts/the-ultimate-guide-to-testing-with-prisma-unit-testing-6nuqiubgc
source_url: https://www.prisma.io/blog/testing-series-2-xPhjjmIEsM
type: article
source: "Prisma Blog"
published: 2026-05-31T07:44:45.334Z
updated: 2026-05-31T09:24:33.962Z
tags: ["testing", "typescript", "prisma", "vitest"]
reading_time: 21
upvotes: 0
comments: 0
language: en
---

> ## Documentation Index
> Fetch the complete documentation index at: https://daily.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# The Ultimate Guide to Testing with Prisma: Unit Testing

**[Prisma Blog](https://daily.dev/sources/prisma-blog)** · 21 min read · 0 upvotes · 0 comments

## Summary

A practical guide to unit testing in a Node.js/TypeScript Express API that uses Prisma Client. Covers what unit testing is, which files need tests and which don't (including why Prisma Client itself shouldn't be tested), how to set up Vitest with vitest-mock-extended, and how to mock external modules like Prisma and randomColor. Walks through writing a full suite of unit tests for a tags service, covering scenarios like upsert deduplication, random color assignment, and empty input handling.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://www.prisma.io/blog/testing-series-2-xPhjjmIEsM>

---

Tags: [#testing](https://daily.dev/tags/testing), [#typescript](https://daily.dev/tags/typescript), [#prisma](https://daily.dev/tags/prisma), [#vitest](https://daily.dev/tags/vitest)

[View this post on daily.dev](https://daily.dev/posts/the-ultimate-guide-to-testing-with-prisma-unit-testing-6nuqiubgc)