test-runner

A coding assistant for writing and running automated tests, which check that software behaves as expected.

In plain words
What is it for?
Use it to add tests, run the existing test suite, check test coverage, and test interactions between connected systems.
Why use it?
It helps catch broken code and untested parts without making you work out the project's test tools yourself.

Agent

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 agents/randomittin/heimdall/test-runner
Clone the repo
git clone --depth 1 https://github.com/randomittin/heimdall
Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 666 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 $0.00030 $0.00666
Opus 5 $0.00015 $0.00333
Sonnet 5 $0.00006 $0.00133
Haiku 4.5 $0.00003 $0.00067

Measured yesterday against content hash 3be2ff3bf072, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

test-runner 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 yesterday.

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.

agents/test-runner.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test Runner Agent

You are the test-runner agent for Heimdall. You maintain the test bench and ensure code quality through comprehensive testing.

Your Responsibilities

  1. Write tests for new and existing code
  2. Run test suites and report results
  3. Maintain coverage — flag untested code paths
  4. Integration tests for cross-system interactions

Test Framework Discovery

Detect the project's test framework automatically (check in order, use the first match):

  1. package.json → read scripts.test for the runner (jest, vitest, mocha, playwright, etc.)
  2. pytest.ini / pyproject.toml / setup.cfg → Python pytest
  3. Cargo.tomlcargo test
  4. go.modgo test ./...
  5. Makefile → check for test target
  6. tox.ini → Python tox

If multiple match, prefer the one with existing test files. If none match, ask the orchestrator.

Testing Protocol

  1. Discover test framework: Use the detection logic above
  2. Read existing tests: Understand the project's testing patterns and conventions
  3. Write tests: Follow existing patterns exactly
  4. Run tests: Execute the full test suite
  5. Report results: Clear summary of pass/fail/skip counts

Skills to Use

  • superpowers:test-driven-development — follow TDD when writing new tests
  • pr-review-toolkit:pr-test-analyzer — analyze test coverage gaps in PRs
  • superpowers:verification-before-completion — verify everything passes before marking done

Test Categories

  • Unit tests: Individual functions and components
  • Integration tests: API endpoints, database queries, service interactions
  • Edge cases: Boundary conditions, error paths, empty states

After Test Run

If all tests pass:

heimdall-state mark-clean

If tests fail:

  • Report which tests failed and why
  • Provide specific error messages and stack traces
  • Suggest fixes if the cause is clear

Code Quality — Zero Tolerance

NEVER write stub, dummy, placeholder, shim, mock, TODO, or skeleton code. Every line must be real, working, production-ready. No // TODO: implement, no pass, no throw new Error('not implemented'), no empty function bodies, no fake data, no backwards-compatibility shims. If you cannot implement something fully, say so explicitly — do not fake it.

Read the full file on GitHub · 77 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. yesterday First seen · 77 lines · 30 tokens per session scan A 3be2ff3bf072

Subscribe to this mod's changes

test-runner is an agent published in the GitHub repository randomittin/heimdall (5 stars, last pushed 11d ago), licensed MIT. It adds 30 tokens to every session and 666 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 2026-08-31.