ExUnit Test Framework

ExUnit Test Framework is a skill for Claude Code, Codex from FortiumPartners/ensemble. It costs 26 tokens per session (1,389 once invoked), scanned A, original, MIT.

A testing helper for Elixir, a programming language. It creates and runs ExUnit tests, which are checks that confirm code behaves as expected.

In plain words
What is it for?
Generating tests from a source file and bug or feature description, organizing tests with setup callbacks and describe blocks, running them through Mix, and returning results as JSON or readable text.
Why use it?
It reduces the manual work of writing test files and collecting test results for Elixir projects.

Skill for Claude CodeCodex

Written for Claude Code and Codex: user-invocable in frontmatter, but also installed under .codex/.

Part of the ensemble-codex plugin — 40 skills shipped together

Good fit Generating tests from a source file and bug or feature description, organizing tests with setup callbacks and describe blocks, running them through Mix, and returning results as JSON or readable text.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fortiumpartners/ensemble/exunit
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 FortiumPartners/ensemble --skill exunit
Clone the repo
git clone --depth 1 https://github.com/FortiumPartners/ensemble

Made for: Claude Code, Codex.

Or install ensemble-codex, the plugin that ships this one along with the rest of its 40 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 ExUnit Test Framework

README.md
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Your own site
<a href="https://agentmods.dev/skills/fortiumpartners/ensemble/exunit"><img src="https://agentmods.dev/badge/skills/fortiumpartners/ensemble/exunit/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 ExUnit Test Framework

Your own site · 80×15
<a href="https://agentmods.dev/skills/fortiumpartners/ensemble/exunit"><img src="https://agentmods.dev/badge/skills/fortiumpartners/ensemble/exunit.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,389 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 $0.00026 $0.01389
Opus 5.5 $0.00010 $0.00556
Sonnet 5.5 $0.00005 $0.00278
Haiku 4.5 $0.00003 $0.00139

Measured 1mo ago against content hash 29741c405b0d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

ExUnit Test Framework 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 1mo 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.

packages/codex/.codex/skills/exunit/SKILL.md · 244 lines

How it starts

The opening of the file, as written. The whole thing — 244 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ExUnit Test Framework

Purpose

Provide ExUnit test execution and generation for Elixir projects, supporting:

  • Test file generation from templates (_test.exs files)
  • Test execution with Mix test integration
  • Setup and setup_all callbacks
  • Describe blocks for test organization
  • Async testing support

Usage

Generate Test File

Create a test file from a bug report or feature description:

elixir generate-test.exs \
  --source lib/calculator.ex \
  --output test/calculator_test.exs \
  --module Calculator \
  --description "Division by zero error"

Execute Tests

Run ExUnit tests and return structured results:

elixir run-test.exs \
  --file test/calculator_test.exs \
  --format json

Command Line Options

generate-test.exs

  • --source <path> - Source file to test (required)
  • --output <path> - Output test file path (required)
  • --module <name> - Module name to test (required)
  • --description <text> - Bug description or test purpose
  • --async - Enable async testing (default: false)

run-test.exs

  • --file <path> - Test file to execute (required)
  • --format <json|doc> - Output format (default: json)
  • --trace - Run with detailed trace

Output Format

Test Generation

Returns JSON with generated test file information:

{
  "success": true,
  "testFile": "test/calculator_test.exs",
  "testCount": 1,
  "template": "unit-test",
  "async": false
}

Test Execution

Returns JSON with test results:

{
  "success": false,
  "passed": 2,
  "failed": 1,
  "total": 3,
  "duration": 0.234,
  "failures": [
    {
      "test": "test divide by zero raises ArithmeticError",
      "error": "Expected ArithmeticError to be raised",
      "file": "test/calculator_test.exs",
      "line": 15
    }
  ]
}

ExUnit Test Structure

Basic Test

defmodule CalculatorTest do
  use ExUnit.Case

  test "adds two numbers" do
    assert Calculator.add(1, 2) == 3
  end
end

With Describe Blocks

Read the full file on GitHub · 244 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. 1mo ago First seen · 244 lines · 26 tokens per session scan A 29741c405b0d

Subscribe to this mod's changes

ExUnit Test Framework is a skill published in the GitHub repository FortiumPartners/ensemble (12 stars, last pushed 7d ago), licensed MIT. It adds 26 tokens to every session and 1,389 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-30.