What is add-assertion?

A development workflow for adding assertion functions to bashunit, a Bash testing framework. TDD, or test-driven development, means writing tests before or alongside the code and using them to guide the implementation.

Use it when adding Bash assertions, documenting acceptance criteria, studying existing project patterns, running RED-GREEN-REFACTOR test cycles, and checking return codes or error messages.

It reduces regressions by requiring success, failure, edge-case, and integration tests for each new assertion.

add-assertion — Skill by TypedDevs

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 skills/typeddevs/bashunit/add-assertion

Any agent

npx skills add TypedDevs/bashunit --skill add-assertion

Clone the repo

git clone --depth 1 https://github.com/TypedDevs/bashunit

Made for: Claude Code, Codex.

Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 430 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.

Model	Per session	Once invoked
Fable 5	$0.00015	$0.00430
Opus 5	$0.00008	$0.00215
Sonnet 5	$0.00003	$0.00086
Haiku 4.5	$0.00002	$0.00043

Measured 2d ago against content hash c47e04081054, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

add-assertion 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.

.claude/skills/add-assertion/SKILL.md · 60 lines

What it actually says

Add Assertion Skill

Add a new assertion function to bashunit following strict TDD methodology.

Prerequisites

Task file must exist — create .tasks/YYYY-MM-DD-add-assertion-name.md
Study patterns — read tests/unit/assert_test.sh and src/assertions.sh

Workflow

1. Plan

Ask user: assertion name, parameters, success/failure behavior, error messages.

Document acceptance criteria and test inventory in task file.

2. Study Existing Patterns

Read src/assertions.sh and tests/unit/assert_test.sh to understand:

Parameter validation, assertion logic, error message format
Return codes (0 = success, 1 = failure)
How tests verify both success and failure cases

3. TDD Cycles

For each test in inventory, follow RED -> GREEN -> REFACTOR:

Basic success case — assertion passes with valid input
Failure case — assertion fails correctly: capture its output and compare it with bashunit::console_results::print_failed_test (there is no assert_fails)
Edge cases — empty input, special characters, nested structures, malformed data

4. Integration

Source new file in src/bashunit.sh if created
export -f the assertion function
Run full test suite: ./bashunit tests/
Quality checks: make sa && make lint

5. Documentation

Add function header with Arguments/Returns/Example
Update CHANGELOG.md
Update user-facing docs if applicable

Final Checklist

All tests passing (success, failure, edge cases)
Function documented and exported
Quality gate passes
CHANGELOG updated
Task file completed

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.

2d ago First seen · 60 lines · 15 tokens per session scan A c47e04081054

Subscribe to this mod's changes

add-assertion is a skill published in the GitHub repository TypedDevs/bashunit (424 stars, last pushed 2d ago), licensed MIT. It adds 15 tokens to every session and 430 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 2026-08-30.

Productivity Testing Writing and docs assertions bash bash-script testing-framework unittesting

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add-assertion