# Add Assertion

> Add new assertion function with comprehensive tests following TDD Use when this capability is needed.

- Skill: `tomevault-io/add-assertion` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/add-assertion`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/add-assertion/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/add-assertion

---


# Add Assertion Skill

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

## Prerequisites

1. **Task file must exist** — create `.tasks/YYYY-MM-DD-add-assertion-name.md`
2. **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:

1. **Basic success case** — assertion passes with valid input
2. **Failure case** — assertion fails correctly, use `assert_fails`
3. **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 && shfmt -w .`

### 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

---
> Converted and distributed by [TomeVault](https://tomevault.io/claim/typeddevs) — claim your Tome and manage your conversions.
<!-- tomevault:4.0:skill_md:2026-04-11 -->