no-tautological-tests

no-tautological-tests is a cursor rule for Codex from prisma/orm. It costs 0 tokens per session (260 once invoked), scanned A, original, Apache-2.0.

A testing rule against tautological tests—tests that only repeat the data they were given instead of checking what the code does.

In plain words
What is it for?
Use it when writing tests to check transformations, branching, errors, integrations, or side effects rather than copied input fields.
Why use it?
Such tests can pass even when important behavior is broken, while adding little useful coverage.

Cursor rule for Codex

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/no-tautological-tests
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 no-tautological-tests

README.md
[![agentmods](https://agentmods.dev/badge/rules/prisma/orm/no-tautological-tests.svg)](https://agentmods.dev/rules/prisma/orm/no-tautological-tests)
Your own site
<a href="https://agentmods.dev/rules/prisma/orm/no-tautological-tests"><img src="https://agentmods.dev/badge/rules/prisma/orm/no-tautological-tests.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 260 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 $0.00260
Opus 5 $0.00000 $0.00130
Sonnet 5 $0.00000 $0.00052
Haiku 4.5 $0.00000 $0.00026

Measured 4d ago against content hash 76c7861ddc5b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

no-tautological-tests 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 4d 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/no-tautological-tests.mdc · 37 lines

What it actually says

Avoid Tautological Tests

Tests must verify behavior, not mirror object shape passed by the test itself.

Rule

  • Prefer assertions that validate transformation, branching, integration behavior, error handling, or side effects.
  • Do not add tests that only confirm an object still contains fields copied directly from the test input.
  • If coverage pressure encourages low-value assertions, tune coverage configuration instead of adding meaningless tests.

Examples

❌ Avoid

const value = makeThing({ a: 1, b: 2 });
expect(value).toMatchObject({ a: 1, b: 2 });

When makeThing() only stores the same input fields, this adds little signal and mostly tests fixture setup.

✅ Prefer

const value = makeThing({ precision: 12 });
expect(value.normalize()).toBe('numeric(12)');
expect(() => makeThing({ precision: -1 })).toThrow();

These assertions validate behavior and error paths that can actually regress.

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. 4d ago First seen · 37 lines · 0 tokens per session scan A 76c7861ddc5b

Subscribe to this mod's changes

no-tautological-tests is a cursor rule published in the GitHub repository prisma/orm (47,594 stars, last pushed yesterday), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 260 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 2026-08-30.