unit-tests

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

.cursor/skills/turborepo

Audit 0.4.1 · source sha 3e61684b2303 · 23 Oct 2026Report an issue or request a re-scan

• Publisherbklit GitHub organizationOwner of the repository this skill is read from
• Source folderbklit/bklit-ui/.agents/skills/unit-testsThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict3e61684b2303A new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Guardrails for adding unit tests in bklit-ui without over-testing. Use when the user mentions unit test, unit tests, tests, test coverage, add tests, write tests, vitest, jest, or asks whether something should be tested.

---
name: unit-tests
description: |
  Guardrails for adding unit tests in bklit-ui without over-testing. Use when the
  user mentions unit test, unit tests, tests, test coverage, add tests, write tests,
  vitest, jest, or asks whether something should be tested.
metadata:
  internal: "true"
---

# Unit Tests (bklit-ui)

Read this skill before proposing or writing tests. **Default stance: fewer, higher-signal tests.**

---

## When to add tests

Add tests when they **lock in behavior that is easy to break silently**:

| Worth testing | Why |
|---------------|-----|
| Pure functions / modules | Stable inputs → outputs; fast; no DOM |
| Formatters, parsers, scale math, bounds | Regression on string/number output is user-visible |
| Codegen / export / registry helpers | Output shape is the contract |
| Non-obvious edge cases | Empty data, reversed ranges, clamping |

**Examples in this repo:** `chart-formatters.test.ts`, `highlight-segment-bounds.test.ts`, `animation.test.ts`, `apps/web/lib/studio/__tests__/*`.

---

## When NOT to add tests (unless explicitly requested)

Do **not** add tests just to increase coverage or “be thorough”:

| Skip | Why |
|------|-----|
| React component render smoke tests | visx, motion, portals → brittle; manual/docs check is cheaper |
| `memo()` / guard extractions (#65-style) | Structural perf refactors; output unchanged; RTL mount assertions are heavy |
| Default prop passthrough | `formatValue = intFmt` — types + formatter tests cover it |
| Third-party library behavior | Don’t re-test d3, visx, or React |
| Trivial getters / one-line wrappers | No regression signal |
| Snapshot entire chart SVG/JSX | High churn, low signal |

If the user asks “should we test X?” — **say no** when X falls in this table, and suggest a lighter alternative (pure helper test, manual check, CI build).

---

## Repo conventions

**Runner:** Node built-in test runner + `tsx` (not Jest/Vitest unless the repo adopts them later).

```bash
pnpm test              # root — turbo runs packages with a test script
pnpm --filter @bklitui/ui test
cd apps/web && pnpm test
```

**Place tests:** `**/__tests__/**/*.test.ts` next to the code under test.

**Pattern:**

```ts
import assert from "node:assert/strict";
import { describe, it } from "node:test";
import { myFn } from "../my-module";

describe("myFn", () => {
  it("handles empty input", () => {
    assert.equal(myFn([]), expected);
  });
});
```

**Equivalence tests** (preferred for formatters): assert shared module output matches the **previous inline** call (e.g. `toLocaleDateString` with same locale/options) so tests stay timezone-safe and prove no visual regression.

**New package test script:** add to `package.json`:

```json
"test": "node scripts/run-tests.mjs"
```

Use a small `scripts/run-tests.mjs` that collects `*.test.ts` from `__tests__` and invokes `node --import tsx --test` — shell globs break on Linux CI. Add `tsx` as a devDependency if missing. Wire into root `turbo.json` `test` task; CI runs `pnpm test`.

---

## Decision checklist (run before writing)

1. Is the logic **pure** or extractable to pure functions? → Test that. Consider extracting first.
2. Would a test fail on a **real user-visible bug**? → Good candidate.
3. Does it need **jsdom / RTL / Playwright**? → Stop; justify to user or defer to manual/visual check.
4. Did the user **ask** for tests? → Still apply this skill; don’t over-deliver.
5. How many cases? → **3–10 focused cases**, not exhaustive matrices.

---

## What to tell the user

When recommending tests, be explicit:

- **Add:** “Test `chart-formatters.ts` — pure, high regression value.”
- **Skip:** “Skip component tests for the memo split — no output change; build + manual chart docs are enough.”
- **CI:** Mention `pnpm test` in PR test plan when adding or changing tests.

---

## Anti-patterns

- Adding Jest/Vitest/Testing Library for a one-off without team buy-in
- Mocking entire chart context to assert `useMemo` call counts
- Testing implementation details (hook order, internal component names)
- Duplicating type-checker work (`expect(typeof x).toBe('function')`)
- Committing tests that only pass locally due to hard-coded timezone/locale strings

Excerpt, first 4,214 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/bklit/bklit-ui
git -C bklit-ui checkout 3e61684b2303

Works in

1. 2026-10-23
   ✓SAFE B 89 / 100

   first audit · source 3e61684b2303

Questions about unit-tests

• github.com/bklit/bklit-ui/tree/main/.agents/skills/unit-tests — the audited source at commit 3e61684b2303 and every finding aboveObserved · 23 Oct 2026

Spotted something wrong? Report a correction · Methodology