vitest-expect-typeof

vitest-expect-typeof is a cursor rule for Cursor from prisma/orm. It costs 0 tokens per session (423 once invoked), scanned A, original, Apache-2.0.

A TypeScript testing rule for replacing Vitest's deprecated toMatchTypeOf matcher with toExtend or toEqualTypeOf. Vitest is a JavaScript and TypeScript testing tool; type matchers check types without running normal value comparisons.

In plain words
What is it for?
It is for checking TypeScript type shapes in Vitest tests, especially when verifying plans or database-related structures.
Why use it?
It avoids deprecated test syntax and distinguishes between compatible types and exactly equal types.

Cursor rule for Cursor ✓ vendor

Written for Cursor: a Cursor rule (.mdc). Also seen: installed under .agents/ (shared by several agents).

Good fit It is for checking TypeScript type shapes in Vitest tests, especially when verifying plans or database-related structures.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/prisma/orm/vitest-expect-typeof
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 · 47,608 stars · on GitHub · prisma.io

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.

Clone the repo
git clone --depth 1 https://github.com/prisma/orm

Made for: Cursor.

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 vitest-expect-typeof

README.md
[![agentmods](https://agentmods.dev/badge/rules/prisma/orm/vitest-expect-typeof.svg)](https://agentmods.dev/rules/prisma/orm/vitest-expect-typeof)
Your own site
<a href="https://agentmods.dev/rules/prisma/orm/vitest-expect-typeof"><img src="https://agentmods.dev/badge/rules/prisma/orm/vitest-expect-typeof.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 423 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00000 $0.00423
Opus 5 $0.00000 $0.00211
Sonnet 5 $0.00000 $0.00085
Haiku 4.5 $0.00000 $0.00042

Measured 3d ago against content hash a76065018071, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

vitest-expect-typeof 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 3d ago.

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/vitest-expect-typeof.mdc · 52 lines

What it actually says

Vitest expectTypeOf API

Deprecated: toMatchTypeOf

The toMatchTypeOf() matcher has been deprecated in Vitest's expectTypeOf API.

Do not use:

expectTypeOf(plan).toMatchTypeOf<Plan<Row>>();

Use toExtend() instead

Use toExtend() to verify that a type extends or matches another type:

Correct usage:

expectTypeOf(plan).toExtend<Plan<Row>>();

When to use toExtend() vs toEqualTypeOf()

  • toExtend<T>(): Verifies that the type extends T (allows subtypes). Use when checking that a value's type matches or is a subtype of the expected type.
  • toEqualTypeOf<T>(): Verifies exact type equality. Use when checking for exact type matches.

For most cases where you're verifying that a plan or object has the correct type structure, toExtend() is the appropriate choice.

Anti-pattern: Manual type checks with conditional types

Do not use manual type checking patterns with conditional types:

// ❌ WRONG: Manual type check pattern
const _textTypeIdCheck: TextTypeId extends 'pg/text@1' ? true : false = true;
const _intTypeIdCheck: IntTypeId extends 'pg/int4@1' ? true : false = true;

Use Vitest's expectTypeOf instead:

// ✅ CORRECT: Use Vitest type helpers
expectTypeOf<TextTypeId>().toEqualTypeOf<'pg/text@1'>();
expectTypeOf<IntTypeId>().toEqualTypeOf<'pg/int4@1'>();

The manual pattern creates unnecessary variables and is less readable. Vitest's expectTypeOf provides clear, declarative type assertions that integrate with the test framework.

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. 3d ago First seen · 52 lines · 0 tokens per session scan A a76065018071

Subscribe to this mod's changes

vitest-expect-typeof is a cursor rule published in the GitHub repository prisma/orm (47,608 stars, last pushed 4d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 423 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.