aggregate-fixtures-writer

aggregate-fixtures-writer is an agent for Claude Code from voro6yov/spec-driven-development. It costs 55 tokens per session (2,877 once invoked), scanned A, original, Apache-2.0.

A generator for pytest fixtures, which are reusable test setup functions, for domain aggregate roots. An aggregate root is the main object that controls a related group of domain objects.

In plain words
What is it for?
Use it to write aggregate fixtures into tests/conftest.py based on the domain specification and its test plan.
Why use it?
It turns the test plan’s state data into consistent setup code and avoids creating separate fixtures for entities that should be tested through their aggregate.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the domain-spec plugin — 2 skills, 1 command, 12 agents shipped together

Good fit Use it to write aggregate fixtures into tests/conftest.py based on the domain specification and its test plan.

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Install with agentmods
npx agentmods add agents/voro6yov/spec-driven-development/aggregate-fixtures-writer
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/voro6yov/spec-driven-development

Made for: Claude Code.

Or install domain-spec, the plugin that ships this one along with the rest of its 2 skills, 1 command, 12 agents.

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 aggregate-fixtures-writer

README.md
[![agentmods](https://agentmods.dev/badge/agents/voro6yov/spec-driven-development/aggregate-fixtures-writer.svg)](https://agentmods.dev/agents/voro6yov/spec-driven-development/aggregate-fixtures-writer)
Your own site
<a href="https://agentmods.dev/agents/voro6yov/spec-driven-development/aggregate-fixtures-writer"><img src="https://agentmods.dev/badge/agents/voro6yov/spec-driven-development/aggregate-fixtures-writer.svg" alt="Measured on agentmods" height="20"></a>
Per session 55 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,877 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 $0.00055 $0.02877
Opus 5 $0.00028 $0.01438
Sonnet 5 $0.00011 $0.00575
Haiku 4.5 $0.00006 $0.00288

Measured 8d ago against content hash 11c21edee1c0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

aggregate-fixtures-writer 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 8d 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.

plugins/domain-spec/agents/aggregate-fixtures-writer.md · 177 lines

How it starts

The opening of the file, as written. The whole thing — 177 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a DDD aggregate fixtures writer. Read the # Test Plan from <stem>.domain/test-plan.md and the class spec from <stem>.domain/specs.md, then generate pytest fixtures for every <<Aggregate Root>> class and write them into <tests_dir>/conftest.py. Do not generate fixtures for <<Entity>> classes — entities are tested through their owning aggregate. Follow the aggregate-fixtures and aggregate-data-fixtures pattern docs for data-fixture decisions and coding style. Do not ask for confirmation before writing.

The State Keys table of the Test Plan is the single source of truth for which fixtures exist and what mutations each applies. Archetype rules from the aggregate-fixtures pattern doc are used only as a completeness check against the State Keys table.

Arguments

  • <domain_diagram>: path to the source diagram file. The plugin folder is derived from its stem:
    • <stem>.domain/specs.md — contains the merged class specification
    • <stem>.domain/test-plan.md — contains the Test Plan written by aggregate-tests-planner
  • <tests_dir>: path to the tests/ directory where conftest.py should be written (must already exist)

Path convention

Per spec-core:naming-conventions, given <domain_diagram> at <dir>/<stem>.md:

  • <stem> = basename of <domain_diagram> with .md suffix stripped
  • Specs file: <dir>/<stem>.domain/specs.md
  • Test plan file: <dir>/<stem>.domain/test-plan.md

Workflow

Step 1 — Load pattern docs

Resolve <patterns_dir> as the directory containing the domain-spec:patterns umbrella SKILL.md (auto-loaded via this agent's frontmatter; its loaded context reveals its location). Before doing any analysis, Read both pattern docs in full, each index.md plus its template.md companion:

  • <patterns_dir>/aggregate-fixtures/index.md + template.md
  • <patterns_dir>/aggregate-data-fixtures/index.md + template.md

If either folder is missing, abort with Error: pattern '<name>' has no folder under the domain-spec:patterns umbrella at <patterns_dir>.

Read the full file on GitHub · 177 lines

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. 8d ago First seen · 177 lines · 55 tokens per session scan A 11c21edee1c0

Subscribe to this mod's changes

aggregate-fixtures-writer is an agent published in the GitHub repository voro6yov/spec-driven-development (4 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 55 tokens to every session and 2,877 once invoked, about $0.0003 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 2026-08-31.

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