Oliver Wolfson
ServicesProjectsContact

Development Services

SaaS apps · AI systems · MVP builds · Technical consulting

Services·Blog
© 2025 O. Wolf. All rights reserved.
developmenttesting
The Minimalist Toolchain for High-Confidence Shipping
Modern AI tools let us build faster than ever. They also make it easier to ship convincing mistakes at speed.
December 17, 2025•O. Wolfson

Modern AI tools let us build faster than ever. They also make it easier to ship convincing mistakes at speed.

The solution isn’t more process or more tools. It’s a small, disciplined toolchain that creates confidence through repeatable gates.

This is the minimalist setup I use to ship SaaS apps with confidence and authority — especially when working with AI assistance.


The Goal: A High-Confidence Machine

The goal isn’t “zero bugs.” That’s unrealistic.

The goal is this:

Every change passes through the same small set of checks that catch the most expensive mistakes early.

To do that, you don’t need a massive QA system. You need a few tools that work together to answer four questions:

  1. Is the code coherent?
  2. Does it violate boundaries?
  3. Does it break critical behavior?
  4. Would we know if it failed in production?

Here’s the entire toolchain that answers those questions.


1. TypeScript (Strict)

TypeScript is the first and cheapest test.

In an AI-assisted workflow, this matters more than ever. AI produces code that looks correct. TypeScript catches code that isn’t coherent.

Strict typing gives you:

  • early feedback
  • structural guarantees
  • protection against “almost right” code

If it doesn’t typecheck, it doesn’t ship.

That rule alone eliminates a surprising number of subtle bugs.


2. ESLint

Linting isn’t about style.

It’s about enforcing constraints.

ESLint catches:

  • incorrect hook usage
  • server/client boundary violations
  • unsafe patterns that slip past type checks
  • accidental complexity

In a modern Next.js app, lint errors are often architectural warnings, not nitpicks.

Treat them seriously.


3. next build

next build is where reality shows up.

It catches:

  • invalid Server Component usage
  • dynamic vs static rendering mistakes
  • environment mismatches
  • runtime assumptions that only fail outside dev mode

A project that “works locally” but fails next build is not production-ready.

Senior developers run builds early and often — not just in CI.


4. Vitest (Unit Tests for Invariants)

Unit tests are not about coverage.

They are about protecting invariants.

Invariants are things that must always be true:

  • permission checks
  • validation rules
  • business constraints
  • idempotency behavior
  • pricing or plan limits

Vitest is fast, lightweight, and good enough for this role.

You don’t need many tests here. You need the right ones.

If a bug would cost you hours to debug later, it deserves a unit test.


5. Playwright (E2E Smoke Tests)

End-to-end tests protect reality.

They answer the only question users care about:

“Does the app actually work?”

A small Playwright suite should cover:

  • authentication
  • the primary create/update flow
  • a permission denial case
  • a critical integration path (billing, webhook, etc.)

Three to eight tests is usually enough.

The goal is confidence, not completeness.


6. Sentry (Runtime Truth)

Tests stop at deployment.

Production is where truth lives.

Error reporting closes the loop by answering:

  • Did something break?
  • Who did it affect?
  • Can we fix it quickly?

This isn’t optional for serious work.

Without runtime visibility, you’re shipping blind — no matter how good your tests are.


Why This Works (Especially with AI)

AI increases:

  • code volume
  • refactor frequency
  • surface area for mistakes

This toolchain creates pressure in the right places:

  • Types catch incoherence
  • Lint catches boundary violations
  • Builds catch runtime mistakes
  • Tests catch broken behavior
  • Sentry catches reality

Each layer is simple. Together, they form a system.


What’s Not Here (On Purpose)

You’ll notice what’s missing:

  • complex state management
  • massive test suites
  • elaborate CI pipelines
  • custom frameworks

Those tools have their place.

But for most SaaS apps, they add complexity before confidence.

This setup does the opposite.


The Senior Takeaway

You don’t need more tools to ship confidently.

You need:

  • a small number of gates
  • run every time
  • that block bad changes early
  • and surface failures clearly

That’s enough to run the machine.

And when the machine works, you can move fast — calmly.

Tags
#ai#shipping#test