# Testing

> Guides ccusage Rust and Node tests. Use when adding or fixing cargo tests, Node test files, CLI snapshots, Claude model pricing, LiteLLM compatibility, or fixture-backed tests.

- Skill: `ccusage/testing` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add ccusage/testing`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ccusage/testing/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: ccusage (https://skillmd.com/u/ccusage)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ccusage/testing

---


# ccusage Testing

The `tdd` skill owns the Red-Green-Refactor loop and the focused runner commands.
This skill owns what is specific to ccusage: fixtures, adapter coverage, pricing and
model behavior, snapshots, CLI output, and package tooling.

- Prefer behavior-focused tests over schema-shape tests, unless schema normalization
  itself is the behavior under test.
- Branching behavior belongs in separate tests or table-driven cases rather than an
  `if` inside a test body.
- Skipped local-data smoke tests are acceptable when real user log directories catch
  schema drift, as long as they pass on clean CI machines.

## Rust

Unit tests sit next to the module they exercise in `#[cfg(test)] mod tests`. When a
large module is split, its tests move with the code instead of staying in `main.rs`.

Read `references/rust.md` for fixtures, snapshots, pricing, and model names.

## Node

Read `references/node-test.md`. Node covers only the package launcher and the Nix-side
JS tooling; production CLI runtime behavior is tested in Rust.