test-blindspots

test-blindspots is a skill for Claude Code from Neeeophytee/finding-unknowns-skills. It costs 61 tokens per session (501 once invoked), scanned A, original, MIT.

A focused way to find important behavior that passing automated tests do not prove. It compares the intended behavior with what the tests actually check and runs small exploratory checks for concrete gaps.

In plain words
What is it for?
Use it to investigate what tests miss for a specific change, such as error paths, state transitions, integrations, or behavior hidden by mocks.
Why use it?
A green test suite only proves the assertions it contains, especially when tests use simplified substitutes instead of the real boundary. This workflow exposes missing transitions, consumer expectations, and shared untested assumptions.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the finding-unknowns plugin — 13 skills shipped together

Good fit Use it to investigate what tests miss for a specific change, such as error paths, state transitions, integrations, or behavior hidden by mocks.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/neeeophytee/finding-unknowns-skills/test-blindspots
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.

Any agent
npx skills add Neeeophytee/finding-unknowns-skills --skill test-blindspots
Clone the repo
git clone --depth 1 https://github.com/Neeeophytee/finding-unknowns-skills

Made for: Claude Code.

Or install finding-unknowns, the plugin that ships this one along with the rest of its 13 skills.

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 test-blindspots

README.md
[![agentmods](https://agentmods.dev/badge/skills/neeeophytee/finding-unknowns-skills/test-blindspots/github.svg)](https://agentmods.dev/skills/neeeophytee/finding-unknowns-skills/test-blindspots)
Your own site
<a href="https://agentmods.dev/skills/neeeophytee/finding-unknowns-skills/test-blindspots"><img src="https://agentmods.dev/badge/skills/neeeophytee/finding-unknowns-skills/test-blindspots/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for test-blindspots

Your own site · 80×15
<a href="https://agentmods.dev/skills/neeeophytee/finding-unknowns-skills/test-blindspots"><img src="https://agentmods.dev/badge/skills/neeeophytee/finding-unknowns-skills/test-blindspots.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 501 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 $0.00061 $0.00501
Opus 5 $0.00030 $0.00251
Sonnet 5 $0.00012 $0.00100
Haiku 4.5 $0.00006 $0.00050

Measured 2d ago against content hash 56695d48b6fd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

test-blindspots 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.

skills/test-blindspots/SKILL.md · 25 lines

How it starts

The opening of the file, as written. The whole thing — 25 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test blindspots

Passing tests establish their assertions under their setup. The gap to investigate is where the implementation and its tests share the same untested assumption.

Steps

  1. Establish the intended behavior and scope from the request, specification, changed code, callers, and relevant tests. Run the relevant baseline when possible. If it is already failing, report that limitation rather than describing it as green.
  2. Compare important behavior with what the tests actually assert. Look for a concrete gap: a mock replacing the boundary being claimed, an untested transition, a missing consumer expectation, or an invariant only exercised on the happy path. Choose by consequence and evidence, not by a generic checklist or coverage percentage.
  3. For each selected gap, state the question and design a small exploratory probe that can distinguish correct from incorrect behavior. Use existing tooling and isolated data. Prefer the actual component over a mock when the mock is the source of uncertainty.
  4. Execute the bounded probes within scope. Record observed behavior and the requirement it contradicts. If intended behavior is unclear, report a specification question; if execution is unavailable, report an untested risk. Neither is a confirmed defect.
  5. For a confirmed failure, preserve a minimal reproducer. Add a focused regression test when test edits are within the task's scope; verify that it fails for the intended reason. Report any deliberately failing reproducer separately from the baseline. Do not silently repair production code.
  6. Finish with confirmed defects first, then consequential untested risks or specification questions, the evidence for each, and what was not examined. Finding no consequential gap is a valid result.

Guardrails

  • Do not equate low coverage with a defect, or green tests with exhaustive correctness. A hypothetical scenario alone is not a finding.
  • Preserve existing tests and assertions. Do not weaken a test, expand the refactor, or install an unrelated testing framework to produce a result.
  • Keep probes away from production data and external side effects unless explicitly authorized. State when a local fixture cannot represent the real boundary.
  • Keep this proportional to the change. Stop when further exploration is unlikely to alter the user's decision.

Read the full file on GitHub · 25 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 · 25 lines · 61 tokens per session scan A 56695d48b6fd

Subscribe to this mod's changes

test-blindspots is a skill published in the GitHub repository Neeeophytee/finding-unknowns-skills (329 stars, last pushed 3d ago), licensed MIT. It adds 61 tokens to every session and 501 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 2026-09-09.

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