Tukuk-OSThe Real Goal
The point of tests is not coverage percentages. It is answering one question with confidence: did my last change break anything that used to work? Anything that answers that question honestly is a valid test system.
For a small Node project, the built-in node:test module and node:assert are enough — no dependencies, no configuration files, no transpilation.
Tests as Plain Scripts
``js
// test/url.test.js
import { test } from 'node:test';
import assert from 'node:assert';
import { embedSrc } from '../src/embed.js';
test('youtube watch links become nocookie embeds', () => {
const out = embedSrc('https://www.youtube.com/watch?v=abc123');
assert.strictEqual(out, 'https://www.youtube-nocookie.com/embed/abc123');
});
test('unknown platforms return null instead of guessing', () => {
assert.strictEqual(embedSrc('https://example.com/video/1'), null);
});
`
Run it with:
`bash`
node --test test/
That is the entire infrastructure. CI can run the same command.
What to Test First (Highest Value per Line)
- Pure functions — URL parsing, formatting, scoring, decision logic. No I/O, instant feedback, they catch the most bugs per line written.
- Boundary values — empty strings, zero results, huge inputs, missing fields. Most production bugs live at the edges.
- One happy-path integration test — boot the app, hit /health
, assert200. This catches "the server does not even start" before your users do.
Skip, for now: pixel-perfect DOM tests, mocking every external call, and testing third-party libraries. Those are expensive and rarely where small projects die.
Test the Thing You Just Fixed
Every bug earns a regression test:
`js`
test('getDocuments wrapper: reads res.results, not the object', () => {
const wrapped = { results: [{ id: 1 }], offset: 0, limit: 1000, total: 1 };
assert.strictEqual(normaliseDocs(wrapped).length, 1);
});
We wrote exactly this after a merge script silently copied zero documents because the client returns { results: [...] }, not an array. The bug cost an evening; the test costs four lines and can never cost us that evening again.
The One-Command Habit
Add a single script your hands know:
`json`
"scripts": {
"test": "node --test test/",
"predeploy": "npm test && node --check src/server.js"
}
node --check` deserves special mention: it catches syntax errors across an entire file in milliseconds — the single cheapest test in the Node ecosystem, and enough to stop shipping a typo that crashes the server on restart.
When to Graduate
You have outgrown plain tests when: assertions get repetitive (add tiny helpers), fixtures sprawl (introduce a fixtures folder), or you need HTTP lifecycle control (then consider a framework — but only then). Most solo projects never need to graduate at all.
Tests are not a tax you pay for being serious. They are the difference between changing your code with confidence and changing it with fear.