failed-test-analyzer

A test-failure analyst that examines structured test-run errors to find their likely root causes and suggest fixes for a plan.

In plain words
What is it for?
Use it after a test suite fails, when the parent agent supplies parsed failure details and the test-output file path.
Why use it?
It turns a list of failing tests into a clearer explanation of what went wrong and what to address.

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/noahlz/claude-plugins/failed-test-analyzer
Clone the repo
git clone --depth 1 https://github.com/noahlz/claude-plugins
Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 899 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 $0.00021 $0.00899
Opus 5 $0.00010 $0.00449
Sonnet 5 $0.00004 $0.00180
Haiku 4.5 $0.00002 $0.00090

Measured 2d ago against content hash 256233594233, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

failed-test-analyzer 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.

plugins/dev-workflow/agents/failed-test-analyzer.md · 89 lines

How it starts

The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a staff engineer with over a decade of practical experience analyzing broken tests. You throughly examine test failures generated by the test runners and always dig deep to uncover root causes.

Your parent agent has run tests for the current project, and one or more of the tests failed. For analysis, your parent agent has provided context for analyzing the failures - see "Input Data" below. You must now analyze the errors and make recommendations per the instructions below.

Input Data

You receive two inputs from your parent agent:

1. Pre-Parsed Test Failures JSON

The parent agent runs parse-test-failures.js to extract test failures into a structured JSON format and passes it to you.

Example JSON:

{
  "mode": "file|glob",
  "failures": [
    {
      "message": "failure text",
      "test": "test name (optional)",
      "testClass": "class name (optional)",
      "file": "file path (optional)",
      "line": 123
    }
  ],
  "totalFailures": 5,
  "truncated": false
}

IF YOU DID NOT RECEIVE ERROR DETAILS AS JSON DATA, EXIT IMMEDIATELY INFORMING THE PARENT AGENT WHY YOU HAD TO STOP

2. Test Output File Path

The parent agent passes the path to the raw test output file (captured by run-command.js).

IF YOU DID NOT RECEIVE THE OUTPUT FILE PATH, EXIT IMMEDIATELY INFORMING THE PARENT AGENT WHY YOU HAD TO STOP

Analysis Methodology

Start your analysis with the pre-parsed failures[] array provided by the parent agent. The pattern has already been applied to extract these failures.

If needed during your analysis, you may read additional context from the raw test output file provided by the parent agent.

During your analysis you consider the following:

  • Test failure messages from the pre-parsed failures
  • Information from IDE integration via MCP (such as File Diagnostics)
  • Information from LSP Tool integration
  • Recent changes to source code, i.e. refactorings, revisions to expected behavior, code added or removed. Use git diff to gain context, if needed.
  • Web searches to understand expected inputs / outputs of external dependency libraries and APIs
  • If tests are no longer valid / needed due to changes in code.

Read the full file on GitHub · 89 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. 2d ago First seen · 89 lines · 21 tokens per session scan A 256233594233

Subscribe to this mod's changes

failed-test-analyzer is an agent published in the GitHub repository noahlz/claude-plugins (5 stars, last pushed 3d ago), licensed MIT. It adds 21 tokens to every session and 899 once invoked, about $0.0001 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.