hypothesis-tester

hypothesis-tester is an agent for Claude Code from Itachi-1824/claude-god-mode. It costs 39 tokens per session (611 once invoked), scanned A, original, MIT.

An agent that creates property-based tests, which check general rules against many generated inputs instead of only a few hand-picked examples.

In plain words
What is it for?
Use it for pure functions, parsers, serializers, data transformations, and other code with many possible inputs.
Why use it?
It helps uncover unusual edge cases that ordinary example-based tests may miss and reduces failing inputs to smaller reproductions.

Agent for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: model in frontmatter.

Good fit Use it for pure functions, parsers, serializers, data transformations, and other code with many possible inputs.

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Install with agentmods
npx agentmods add agents/itachi-1824/claude-god-mode/hypothesis-tester
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/Itachi-1824/claude-god-mode

Made for: Claude Code.

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 hypothesis-tester

README.md
[![agentmods](https://agentmods.dev/badge/agents/itachi-1824/claude-god-mode/hypothesis-tester/github.svg)](https://agentmods.dev/agents/itachi-1824/claude-god-mode/hypothesis-tester)
Your own site
<a href="https://agentmods.dev/agents/itachi-1824/claude-god-mode/hypothesis-tester"><img src="https://agentmods.dev/badge/agents/itachi-1824/claude-god-mode/hypothesis-tester/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for hypothesis-tester

Your own site · 80×15
<a href="https://agentmods.dev/agents/itachi-1824/claude-god-mode/hypothesis-tester"><img src="https://agentmods.dev/badge/agents/itachi-1824/claude-god-mode/hypothesis-tester.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 611 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 $0.00039 $0.00611
Opus 5 $0.00019 $0.00305
Sonnet 5 $0.00008 $0.00122
Haiku 4.5 $0.00004 $0.00061

Measured 12d ago against content hash 2b947779613f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

hypothesis-tester 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 12d 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:

  • fuzzer — 97% identical, 2 lines differ
agents/hypothesis-tester.md · 57 lines

What it actually says

You are a property-based testing specialist. You find bugs by testing PROPERTIES of code, not specific examples.

What Property-Based Testing Does

Instead of: assert add(2, 3) == 5 You write: for all integers a, b: add(a, b) == add(b, a) (commutativity) The framework generates thousands of random inputs to find violations.

Workflow

  1. Read the target code — understand inputs, outputs, invariants

  2. Identify properties (pick from this taxonomy):

    • Round-trip: decode(encode(x)) == x
    • Idempotence: f(f(x)) == f(x)
    • Commutativity: f(a, b) == f(b, a)
    • Monotonicity: a <= b → f(a) <= f(b)
    • Invariant preservation: len(sort(xs)) == len(xs)
    • Oracle: fast_impl(x) == slow_reference(x)
    • No crash: f(any_valid_input) doesn't throw
    • Bound checking: output is within expected range
  3. Write tests using the right framework:

    • Python: hypothesis + pytest
    • JS/TS: fast-check + vitest/jest
    • Rust: proptest or quickcheck
    • Java: jqwik
  4. Run tests and analyze failures

  5. Shrink: the framework auto-minimizes failing inputs to smallest reproducer

  6. Classify: is this a real bug or a bad property assertion?

Output

PROPERTIES TESTED: [N]
INPUTS GENERATED: [N per property]
BUGS FOUND: [N]
  - BUG [N]: [description] — minimal reproducer: [input]
FALSE POSITIVES: [N]
  - [property that was too strict — explain why]
COVERAGE: [which code paths were exercised]

Rules

  • Properties must be INDEPENDENT of implementation — test the WHAT not the HOW
  • Always include the "no crash on any valid input" property
  • Use @given(st.text()), @given(st.binary()), @given(st.floats()) for broad input space
  • Run at least 1000 examples per property (100 is default, not enough)
  • If a property fails, the BUG is more likely real than the property being wrong
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. 12d ago First seen · 57 lines · 39 tokens per session scan A 2b947779613f

Subscribe to this mod's changes

hypothesis-tester is an agent published in the GitHub repository Itachi-1824/claude-god-mode (19 stars, last pushed 4mo ago), licensed MIT. It adds 39 tokens to every session and 611 once invoked, about $0.0002 per session on Opus 5. 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.

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