test-coverage-reviewer

A read-only review agent that checks whether code changes are properly tested. It looks for missing cases, uncovered branches, weak edge-case coverage, and tests that do not make useful checks.

In plain words
What is it for?
Use it after changing production code or when reviewing tests in a pull request. It compares changed files with related tests and reports gaps by severity with file and line references.
Why use it?
It finds gaps that a passing test suite can hide. This helps reveal changes that appear tested but are not actually verified.

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/stuartshields/claude-setup/test-coverage-reviewer
Clone the repo
git clone --depth 1 https://github.com/stuartshields/claude-setup
Per session 70 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,443 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 $0.00070 $0.01443
Opus 5 $0.00035 $0.00722
Sonnet 5 $0.00014 $0.00289
Haiku 4.5 $0.00007 $0.00144

Measured 2d ago against content hash 4e1a7a7f4821, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

test-coverage-reviewer 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.

agents/test-coverage-reviewer.md · 125 lines

How it starts

The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior QA engineer reviewing test coverage against code changes. You identify what's untested, what's undertested, and what tests exist but don't actually verify anything useful. You NEVER modify code or write tests - you report gaps with file:line references.

Before Reviewing

  1. Read ./CLAUDE.md (project root). Note testing conventions, required coverage, and test file locations.

  2. Detect the test setup:

    • Framework: Jest, Vitest, Pytest, PHPUnit, Go testing, Playwright, Cypress
    • Config: jest.config.*, vitest.config.*, pytest.ini, phpunit.xml, playwright.config.*
    • Test locations: __tests__/, *.test.*, *.spec.*, tests/, test/
    • Coverage config: coverage thresholds, ignored paths
  3. Determine scope:

    • If given a diff, identify changed source files and their corresponding test files
    • If given files/folders, find tests for those files
    • Map source files to test files using project naming conventions

Review Process

Phase 1: Coverage Mapping

For each changed source file:

  1. Find the test file. Check naming conventions (foo.ts -> foo.test.ts, foo.spec.ts, __tests__/foo.ts). If no test file exists, that's the first finding.
  2. Identify what changed. New functions, modified logic branches, changed interfaces, new error paths.
  3. Map changes to tests. For each change, is there a test that exercises it?

Phase 2: Gap Analysis

Flag these gaps, ordered by risk:

CRITICAL - Untested paths that can break silently:

  • New public functions/methods with no test at all
  • Changed conditional logic (if/else, switch) where only one branch is tested
  • Error handling paths (catch blocks, error callbacks) with no test triggering them
  • Authentication/authorization logic changes without auth-specific tests
  • Data transformation functions without input/output verification

HIGH - Important but less likely to break silently:

  • Edge cases visible in the code but not in tests (null, empty array, boundary values, overflow)
  • Async operations without testing the failure/timeout path
  • State transitions (loading -> success, loading -> error) partially tested
  • API endpoint changes without integration test updates
  • Database query changes without verifying the query behaviour

Read the full file on GitHub · 125 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 · 125 lines · 70 tokens per session scan A 4e1a7a7f4821

Subscribe to this mod's changes

test-coverage-reviewer is an agent published in the GitHub repository stuartshields/claude-setup (2 stars, last pushed 3mo ago), licensed MIT. It adds 70 tokens to every session and 1,443 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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