test-mocking-patterns

test-mocking-patterns is a cursor rule for Codex from prisma/orm. It costs 0 tokens per session (214 once invoked), scanned A, original, Apache-2.0.

A set of TypeScript testing patterns for creating safe, minimal mocks, including mocks of class instances. It explains where test-only type assertions are acceptable.

In plain words
What is it for?
It helps write unit and integration tests with focused mocks and clearly contained type escapes.
Why use it?
It avoids brittle mocks that lose class methods or scatter unsafe type casts throughout tests.

Cursor rule for Codex

About the project

Prisma ORM is a Node.js and TypeScript database toolkit that lets applications work with databases through a programming interface instead of writing every query directly in SQL. Developers use it with databases including PostgreSQL, MySQL, MariaDB, SQL Server, SQLite, MongoDB, and CockroachDB. The catalogue add-ons provide agent rules, skills, hooks, agents, and other workflows for using Prisma.

prisma/orm · 47,601 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/prisma/orm/test-mocking-patterns
Clone the repo
git clone --depth 1 https://github.com/prisma/orm

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for test-mocking-patterns

README.md
[![agentmods](https://agentmods.dev/badge/rules/prisma/orm/test-mocking-patterns.svg)](https://agentmods.dev/rules/prisma/orm/test-mocking-patterns)
Your own site
<a href="https://agentmods.dev/rules/prisma/orm/test-mocking-patterns"><img src="https://agentmods.dev/badge/rules/prisma/orm/test-mocking-patterns.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 214 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00214
Opus 5 $0.00000 $0.00107
Sonnet 5 $0.00000 $0.00043
Haiku 4.5 $0.00000 $0.00021

Measured yesterday against content hash caa802cc8910, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

test-mocking-patterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.agents/rules/test-mocking-patterns.mdc · 31 lines

What it actually says

Test Mocking Patterns

Type assertions in tests

Allowed in tests only:

  • @ts-expect-error (with a short reason)
  • Double casts (as unknown as X) for mocks / dynamic proxies

Prefer unknown over any to keep the unsafe boundary explicit.

Mocking class instances

Rule: Don’t spread ({ ...instance }) class instances in tests — you’ll lose prototype methods.

const mocked = Object.create(Object.getPrototypeOf(original));
Object.assign(mocked, original, { verify: mockedVerify });

When a test mock needs a cast

  • Keep the mock shape minimal (only fields you need)
  • Put the cast at the boundary (return statement), not sprinkled throughout the test
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 31 lines · 0 tokens per session scan A caa802cc8910

Subscribe to this mod's changes

test-mocking-patterns is a cursor rule published in the GitHub repository prisma/orm (47,601 stars, last pushed 2d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 214 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.