tdd

A test-first workflow for detection rules. TDD means writing tests before the rule: one malicious example, one similar but harmless example, then the rule and record validation.

In plain words
What is it for?
Adding or changing detection rules, testing both positive and negative cases, and validating the resulting record files.
Why use it?
It catches rules that miss real cases, flag harmless files, or create invalid records before the full test suite is run.

Skill for Claude CodeCodex

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 skills/aveproject/ave/tdd
Any agent
npx skills add aveproject/ave --skill tdd
Clone the repo
git clone --depth 1 https://github.com/aveproject/ave

Made for: Claude Code, Codex.

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 249 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 $0.00249
Opus 5 $0.00000 $0.00125
Sonnet 5 $0.00000 $0.00050
Haiku 4.5 $0.00000 $0.00025

Measured 2d ago against content hash 55ae3ed36749, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

tdd 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 2d 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.

.claude/skills/tdd/SKILL.md · 30 lines

What it actually says

tdd — ave

For this repo, TDD means: fixtures first, then rule, then record validation.

Loop for a new rule

  1. Write the positive fixture (the malicious file)
  2. Write the negative fixture (the benign lookalike)
  3. Write a test asserting the rule fires on positive, not on negative → FAIL
  4. Write the rule → test PASSES
  5. Write the AVE record JSON
  6. python scripts/validate_records.py → record valid
  7. pytest tests/ -x -q → full suite green

What/Why/How on validation functions

# What: returns True if every record in records/ validates against the schema
# Why:  one malformed record breaks every scanner that loads the record set
# How:  loads each JSON, runs jsonschema.validate, collects all errors
def all_records_valid() -> tuple[bool, list[str]]:
    ...

The negative fixture rule

Every rule needs a negative fixture that looks SIMILAR to the positive but is benign. A rule with only a positive fixture is a false-positive waiting to happen. Test that the rule does NOT fire on the negative.

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. 2d ago First seen · 30 lines · 0 tokens per session scan A 55ae3ed36749

Subscribe to this mod's changes

tdd is a skill published in the GitHub repository aveproject/ave (17 stars, last pushed 3d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 249 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.