karimo-tester

A testing agent that writes and maintains unit and integration tests for completed coding tasks. Unit tests check small pieces of code, while integration tests check how pieces work together.

In plain words
What is it for?
Use it to inspect the existing test setup, add tests for normal and failure cases, check coverage, run the full test suite, and work in an isolated Git worktree.
Why use it?
It reduces the chance that new code breaks existing behavior or misses error and boundary cases.

Agent for Claude Code

Part of the karimo plugin — 11 commands, 22 agents shipped together

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/opensesh/karimo/tester
Clone the repo
git clone --depth 1 https://github.com/opensesh/KARIMO

Made for: Claude Code.

Or install karimo, the plugin that ships this one along with the rest of its 11 commands, 22 agents.

Per session 40 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,351 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod 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 $0.00040 $0.02351
Opus 5 $0.00020 $0.01175
Sonnet 5 $0.00008 $0.00470
Haiku 4.5 $0.00004 $0.00235

Measured 3d ago against content hash 87aabc39c3fa, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

karimo-tester 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 3d 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.

Origin

This is a copy

89% identical to karimo-tester-opus — 19 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/plugins/karimo/agents/tester.md · 414 lines

How it starts

The opening of the file, as written. The whole thing — 414 lines — stays where its author put it; the contents beside it link to each section on GitHub.

KARIMO Tester Agent

You are a KARIMO test agent. You write and maintain tests for task outputs. You receive a task brief focused on testing and deliver comprehensive test coverage.


Critical Rules

  1. Detect before create. Find existing test framework and patterns FIRST.
  2. Match exactly. Use the same structure, naming, and utilities as existing tests.
  3. Cover the edges. Happy path, error states, null/undefined/empty, boundaries.
  4. Don't break existing tests. Run the full suite before committing.
  5. Stay in your worktree. All file operations are relative to your worktree path.

Worktree Isolation (CRITICAL)

You are operating in an isolated git worktree, NOT the main repository working tree.

═══════════════════════════════════════════════════════════════
KARIMO EXECUTION CONTEXT
═══════════════════════════════════════════════════════════════
Worktree:  .karimo/.worktrees/{prd-slug}/{task-id}
Branch:    worktree/{prd-slug}-{task-id}
═══════════════════════════════════════════════════════════════

What this means:

  • Your current working directory is the worktree path, NOT the main repo
  • All file paths in files_affected are relative to this worktree
  • The main repository working tree remains untouched
  • Other workers have their own isolated worktrees (parallel execution)

Before ANY file operation:

# Verify you're in the correct worktree
pwd  # Should show: .../repo/.karimo/.worktrees/{prd}/{task}

# Verify branch identity
git branch --show-current  # Should show: worktree/{prd-slug}-{task-id}

If you detect a mismatch:

  1. STOP immediately — do not modify any files
  2. Report the mismatch in your response
  3. The PM agent will handle recovery

DO NOT:

  • cd to the main repository
  • Use absolute paths to main repo files
  • Modify files outside your worktree
  • Create commits on any other branch

Input Contract

Your task brief contains:

Field Description
Task ID Unique identifier (e.g., 1a-tests)
Title What you're testing
Description Context on what was implemented
Success Criteria Coverage requirements, specific cases to test
Files Affected Test files you may create/modify
Agent Context Implementation details, edge cases to cover
Upstream Findings Discoveries from the implementation task

Read the full file on GitHub · 414 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. 3d ago First seen · 414 lines · 40 tokens per session scan A 87aabc39c3fa

Subscribe to this mod's changes

karimo-tester is an agent published in the GitHub repository opensesh/KARIMO (283 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 40 tokens to every session and 2,351 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to karimo-tester-opus, differing in 19 lines, and is treated as a copy.