What Is Vibe Coding?

Vibe codingis a new trend in software development where developers use AI tools like ChatGPT or GitHub Copilot to generate code by describing functionality in plain English. Popularized by Andrej Karpathy, vibe coding flips traditional coding:
You describe → AI writes → you tweak → it runs.

“I see stuff, say stuff, run stuff.” – The unofficial motto of vibe coding.

It feels like pair-coding with a genius intern. But in this creative whirlwind of AI-assisted generation, one question remains:
Does unit testing still matter?

Why Vibe Coding Is So Popular

Vibe coding is growing fast — for good reason:

• 🚀 Rapid prototyping: Build working code in hours, not days
• 🤖 AI handles boilerplate: Focus on logic, not syntax
• 👶 Accessible for non-experts: Great for juniors and product teams
• 🎯 Flow-state coding: Faster iterations with minimal friction

It feels like playing jazz: expressive, improvised, and powerful.

But here’s the catch: AI can write plausible code — not always correct code.

The Risk: Code You Don’t Fully Understand

In vibe coding, you often:

• Don’t write most of the code
• Don’t fully read every generated line
• Don’t test deeply before running

That opens the door to:

• ❌ Hidden logic bugs
• 🔓 Security flaws
• 🧟 Code you can’t maintain or refactor

So how do you keep your AI-generated code safe and reliable?

Unit Testing: The Secret Sauce for Safe Vibe Coding

Let’s be clear:
Unit testing doesn’t break the vibe — it protects it.

Here’s why:

✅ 1. Catch Errors the AI Missed

AI doesn’t understand your business rules. Unit tests ensure your code behaves the way it should — even when it looks right syntactically.

🔄 2. Create Fast Feedback Loops

Vibe coding is iterative. So is unit testing.
Write a test → run the AI → test again → repeat.

🔒 3. Refactor with Confidence

If the AI produces spaghetti code, tests give you the confidence to clean it up. You’re free to restructure, knowing your tests have your back.

🧠 4. Understand Behavior, Not Just Code

Tests don’t just validate logic — they document expected behavior, especially useful when you didn’t write the original code.

Unit Testing in Vibe Coding with Typemock

Vibe coding thrives when paired with tools that don’t get in your way.

Enter Typemock.

With Typemock Isolator for .NET and Isolator++ for C++, you can:

• 🧪 Mock anything — sealed, static, or legacy code
• ⚙️ Test AI-generated code without refactoring
• 🛠 Use Arrange-Act-Assert style to create readable, robust tests
• 🐧 Now support Linux/GCC 5.4+ and C++14 — native, no wrappers

Whether the code is yours or the AI’s, you can mock, isolate, and test like a pro.

How to Integrate Unit Testing into Vibe Coding

Here’s the new vibe‑dev loop:

1. ✍ Prompt the AI to generate a method or class
2. 👀 Skim the output — understand the logic (roughly)
3. 🧪 Write unit tests to define expected behavior
4. 🔁 Ask the AI to revise code based on test feedback
5. ♻️ Repeat until green
6. 🔒 Ship with confidence

That’s not just testing — it’s vibe-safe development.

See why vibe-coding needs more than vibes

Final Verdict: Vibe Coding + Unit Testing = Power + Safety

Vibe coding is transforming how we write software. But if you’re only relying on AI and skipping tests, you’re building on sand.

With the right tools — like Typemock — unit testing doesn’t slow the vibe.
It amplifies it.

So vibe on. Just make sure your tests are vibing too.

🔧 Ready to vibe safely?

👉 Download Typemock Isolator

Read more:
Vibe Coding Wikipedia
Andrej Karpathy YouTube: Vibe Coding
WSJ: Vibe Coding for Business

The post Does Unit Testing Fit In with AI‑Driven Vibe Coding? appeared first on Typemock.

Jake Knapp and John Zeratsky are the co-creators of the Design Sprint (the famous five-day product innovation process) and authors of the bestselling book Sprint. After decades of working with over 300 startups in the earliest stages, they discovered that most startups fail not because they can’t build, but because they build the wrong thing. The very beginning of a startup is your highest-leverage moment, and most teams waste months or years by skipping a few critical early questions. Jake and John developed the Foundation Sprint to help startups validate ideas and compress months of work into just two days.

What you’ll learn:

1. The step-by-step Foundation Sprint process that compresses three or four months of validation into two days—including templates you can use immediately

2. Why differentiation is the #1 predictor of startup success (with the 2x2 framework that you can use with your team)

3. The three fundamental questions every founder should answer before writing a line of code

4. The “note and vote” technique that eliminates groupthink and gets honest answers from your colleagues

5. The seven “magic lenses” for choosing between multiple product ideas

6. The biggest mistake engineers make when building with AI tools

7. The paradox of speed: why “building nothing first” can get you to product-market fit faster

—

Brought to you by:

Brex—The banking solution for startups: https://www.brex.com/product/business-account?ref_code=bmk_dp_brand1H25_ln_new_fs

Paragon—Ship every SaaS integration your customers want: https://www.useparagon.com/lenny

Coda—The all-in-one collaborative workspace: https://coda.io/lenny

—

Transcript: https://www.lennysnewsletter.com/p/the-foundation-sprint-jake-knapp-and-john-zeratsky

—

Where to find Jake Knapp:

• X: https://twitter.com/jakek

• LinkedIn: https://www.linkedin.com/in/jake-knapp/

• Website: https://jakeknapp.com/

—

Where to find John Zeratsky:

• X: https://twitter.com/jazer

• LinkedIn: https://www.linkedin.com/in/johnzeratsky/

• Website: https://johnzeratsky.com/

—

In this episode, we cover:

(00:00) Introduction to Jake Knapp and John Zeratsky

(04:41) Origins of the Design Sprint

(11:06) The Foundation Sprint process

(14:40) Phase one: The basics

(16:57) Case study: Latchet

(28:50) Phase two: Differentiation

(36:24) The importance of differentiation

(40:15) Thoughts on price differentiation

(43:37) Case study: Mellow

(46:04) Custom differentiators

(49:30) The mini manifesto

(52:02) Phase three: Approach to the project

(54:50) Magic lenses activity

(01:02:39) Prototyping and testing

(01:10:00) Real-world examples and success stories

(01:15:15) Motivation behind The Foundation Sprint

(01:17:15) The outcome of the sprint: The founding hypothesis

(01:19:28) The Design Sprint

(01:28:19) The role of AI in prototyping

(01:36:50) Final thoughts and resources

—

Referenced:

• Introducing the Foundation Sprint: From the creators of the Design Sprint: https://www.lennysnewsletter.com/p/introducing-the-foundation-sprint

• Making time for what matters | Jake Knapp and John Zeratsky (authors of Sprint and Make Time, co-founders of Character Capital): https://www.lennysnewsletter.com/p/making-time-for-what-matters-jake

• Eli Blee-Goldman on LinkedIn: https://www.linkedin.com/in/eli-blee-goldman/

• Character Capital: https://www.character.vc/

• Character Labs: https://www.character.vc/labs

• Etsy: https://www.etsy.com/

• Shopify: https://www.shopify.com/

• Naming expert shares the process behind creating billion-dollar brand names like Azure, Vercel, Windsurf, Sonos, Blackberry, and Impossible Burger | David Placek (Lexicon Branding): https://www.lennysnewsletter.com/p/naming-expert-david-placek

• Sonos: https://www.sonos.com/

• Vercel: https://vercel.com/

• Windsurf: https://windsurf.com/

• April Dunford on product positioning, segmentation, and optimizing your sales process: https://www.lennysnewsletter.com/p/april-dunford-on-product-positioning

• Positioning: https://www.lennysnewsletter.com/p/positioning

• 10 things we know to be true: https://about.google/company-info/philosophy/

• Gandalf: https://en.wikipedia.org/wiki/Gandalf

• Frodo: https://en.wikipedia.org/wiki/Frodo_Baggins

• Mordor: https://en.wikipedia.org/wiki/Mordor

• 35 years of product design wisdom from Apple, Disney, Pinterest, and beyond | Bob Baxley: https://www.lennysnewsletter.com/p/35-years-of-product-design-wisdom-bob-baxley

• The Primal Mark: How the Beginning Shapes the End in the Development of Creative Ideas: https://www.gsb.stanford.edu/faculty-research/publications/primal-mark-how-beginning-shapes-end-development-creative-ideas

• Base44: https://base44.com/

• Solo founder, $80M exit, 6 months: The Base44 bootstrapped startup success story | Maor Shlomo: https://www.lennysnewsletter.com/p/the-base44-bootstrapped-startup-success-story-maor-shlomo

• Google Meet: https://meet.google.com/

• Blue Bottle Coffee: https://bluebottlecoffee.com

• Reclaim: https://reclaim.ai/

• The official Foundation Sprint + Design Sprint template: https://www.character.vc/miro-template

• Rippling: https://www.rippling.com/

• Latchet: https://latchet.com/

• Mellow: http://getmellow.com/

• AxionOrbital: https://axionorbital.space/

—

Recommended books:

• Sprint: How to Solve Big Problems and Test New Ideas in Just Five Days: https://www.amazon.com/Sprint-audiobook/dp/B019R2DQIY

• Make Time: How to Focus on What Matters Every Day: https://www.amazon.com/Make-Time-Focus-Matters-Every/dp/0525572422

• Click: How to Make What People Want: https://www.amazon.com/Click-Make-What-People-Want/dp/1668072114

Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email podcast@lennyrachitsky.com.

—

Lenny may be an investor in the companies discussed.

I've been a bit quiet on this blog recently mainly because I've been busy working on a new Pluralsight course Microservices: Architectural Strategies and Techniques, which essentially replaces my previous Microservices Fundamentals course, although they cover slightly different topics. In this course, I wanted to make sure I addressed some of the "pushback" against microservices, as it's fair to say that there has been some legitimate questions asked about whether microservices are being applied to problems where they don't actually help.

However despite their challenges, I do think there are situations in which microservices can make a lot of sense. And that's because when a software product becomes large enough, with many teams of developers, and many user-facing websites or applications, and many APIs, then it's inevitable that it becomes a distributed system.

In some ways you can think of microservices as simply a more disciplined approach to distributed systems, where you take care to ensure that each service is independently deployable. This helps you avoid the pitfall of building a "distributed monolith" - an architecture famous for combining the worst aspects of both monoliths and distributed systems.

In fact, the majority of the tools, techniques and strategies I discuss in the course are not strictly specific to microservices. That's because most of the key concerns about observability, security, scalability, testability, automated deployment are things that you'll need in a distributed system regardless of whether you are explicitly trying to create "microservices".

Are Microservices Becoming Easier?

One of the hopes in the early days of microservices was that over time, we'd develop tooling that helped us overcome many of the challenges of building, testing, and deploying distributed systems.

In some ways that is true. For example, Kubernetes is incredibly powerful and flexible and has established itself as the de-facto standard for hosting microservices. However, I certainly wouldn't describe it as simple to learn and manage. But we are seeing the emergence of simplified microservices hosting platforms, such as Azure Container Apps which is built on top of Kubernetes, but takes away a lot of the complexity and streamlines the process of hosting your microservices.

Another favourite toolkit of mine for building microservices is Dapr, which offers a set of "building blocks", to enable you to build secure and reliable microservices. I've actually created a Dapr Fundamentals Pluralsight course. The way Dapr delivers these capabilities is by exposing APIs from a sidecar container. This approach has the benefit of making Dapr programming language agnostic, and cloud-agnostic as the building blocks each offer a variety of backing services to implement the capability, giving you a lot of freedom to use the languages and services you are familiar with.

In the .NET world, .NET Aspire aims to improve the experience of building microservices by providing various tools, templates and packages that especially enhance the local development experience. So it does feel like things are moving in the right direction towards simplifying the overall microservices experience.

And in my Pluralsight course I also wanted to include a brief section exploring the ways in which AI is able to streamline the experience of building, deploying and managing microservice applications. A lot of the pain points of microservices revolve around the complexities of managing a system made up of so many interconnected parts. It's still early days for AI, but I am hopeful that it could make a big difference especially in the area of monitoring and troubleshooting distributed systems.

Summary

Microservices remain an valuable architectural pattern, despite the potential troubles you can run into with them. Generally, my architectural preference is to keep things as simple as possible, and only reach for more advanced patterns and tools when you have proved that you really need them. So most of the tools and techniques I show in the course are not so much a prescription of what you should do, as suggestions for things you might reach for if you're experiencing the problems they're designed to solve. If you're a Pluralsight subscriber, why not check out my Microservices: Architectural Strategies and Techniques course, and as always I'm very interested in learning from other people's experiences so do feel free to get in touch via the comments.

On July 14 at 18:00 CEST, join us on Discord for COD#5, hosted by RavenDB performance wizardFederico Lois.

Based in Argentina and known for pushing RavenDB to its limits, Federico will walk us through:

• How we used GenAI to build a code analysis MCP (Model Context Protocol) server

• Why this project is different: it was built almost entirely by AI agents

• Tips for using AI agents to boost your own development velocity with RavenDB

If you’re building fast, scaling smart, or just curious how AI can do more than generate text, this is one to watch!

🚀 The Problem That Started It All

Picture this: You're deep in a coding session, researching solutions across dozens of tabs, bookmarking useful resources left and right. Days later, you're trying to remember that perfect Stack Overflow answer or that brilliant documentation page you found. Sound familiar? 😅

As a SRE Engineer, I constantly juggle between AWS docs, Terraform modules, GitHub repos, and countless other resources. Traditional bookmark managers felt disconnected from my workflow, especially when I started using AI tools like Claude for development tasks.

That's when I discovered the Model Context Protocol (MCP) - a game-changer that bridges the gap between AI assistants and external tools. 🌉

🎯 What is Model Context Protocol?

MCP is like a universal translator between AI models and external systems. Instead of manually copying and pasting information, your AI assistant can directly interact with your tools, databases, and services. Think of it as giving your AI superpowers! ⚡

🛠️ Enter: bookmark-manager-mcp

I built a bookmark management system that integrates seamlessly with Claude and other MCP-compatible clients. Here's what makes it special:

✨ Key Features

• 📁 Persistent Storage: Your bookmarks live in ~/.data/bookmarks.json - simple, portable, and version-control friendly
• 🏷️ Smart Categorization: Organize bookmarks with custom categories (mcp, aws, terraform, general, etc.)
• 🔍 Resource Discovery: Browse bookmarks by category using MCP resources
• 🐳 Docker Ready: One-liner deployment with Docker
• ⚡ TypeScript Power: Type-safe implementation with Zod validation
• 🤖 AI Integration: Ask Claude to manage your bookmarks naturally!

🎪 The Magic in Action

Instead of manually managing bookmarks, you can now chat with Claude:

"Add a bookmark for OpenAI docs at https://docs.openai.com in the AI category"
"Show me all my AWS-related bookmarks"
"Find that Terraform module I bookmarked last week"

And Claude handles it all! 🎉

🔧 Technical Deep Dive

Architecture That Just Works

Why These Tech Choices? 🤔

TypeScript + Zod: Because runtime validation saves you from 3 AM debugging sessions when someone passes malformed URLs 😴

Docker: One command deployment across any environment. No "it works on my machine" scenarios! 🐳

JSON Storage: Simple, readable, and easy to backup. Sometimes the simplest solution is the best solution 📄

MCP SDK: Future-proof integration with the growing MCP ecosystem 🌱

🚀 Getting Started (It's Easier Than You Think!)

Docker

# Pull and run - that's it!
docker pull mindriftfall2infinitepiio/bookmark-manager-mcp:v1.0.0
claude mcp add bookmark-manager -- docker run \
  --rm \
  --interactive \
  --volume ~/.data:/app/.data \
  mindriftfall2infinitepiio/mcp:bookmark-manager-v1.0.0

Enterprise-Ready Backup & Sync

The project includes ready-to-use AWS S3 sync functions for enterprise environments. Your bookmarks stay safe and accessible across devices and teams! ☁️
Use below function to copy the data from local to s3 or s3 to local: get the script from here.

# Sync local bookmarks to S3 (BYOS3 - Bring Your Own S3)
bookmark_sync_to_local_tos3()

# Sync S3 bookmarks to local
bookmark_sync_to_s3_to_local()

🎨 Real-World Usage Examples

For DevOps Engineers 👷‍♂️

{
  "title": "AWS EKS Best Practices",
  "url": "https://aws.github.io/aws-eks-best-practices/",
  "category": "aws"
}

For Developers 👨‍💻

{
  "title": "TypeScript Handbook",
  "url": "https://www.typescriptlang.org/docs/",
  "category": "typescript"
}

For AI Enthusiasts 🤖

{
  "title": "Model Context Protocol",
  "url": "https://modelcontextprotocol.io/introduction",
  "category": "mcp"
}

🌟 Key Breakthrough Features

1. Natural Language Bookmark Management

No more right-clicking and navigating through folder hierarchies. Just tell Claude what you want, and it happens! 🗣️

2. Context-Aware Recommendations

Claude can suggest relevant bookmarks based on your current conversation context. Working on AWS Lambda? It'll show your serverless bookmarks automatically! 🎯

3. Seamless Backup & Sync

Added AWS S3 sync functions for backing up your bookmarks. Your data stays safe and accessible across devices! ☁️

🚧 Challenges & Solutions

Challenge 1: Data Persistence 📊

Problem: Where to store bookmarks safely?
Solution: Local JSON file with configurable paths and Docker volume mounting as backing up the data to S3 with BYOS3(Bring your own s3)

Challenge 2: URL Validation 🔗

Problem: Users might input malformed URLs
Solution: Zod schema validation with helpful error messages

Challenge 3: Category Management 📁

Problem: How to organize bookmarks efficiently?
Solution: Dynamic category creation with MCP resource discovery

🔮 What's Next?

• 🔍 Full-text search across bookmark titles and descriptions
• 📊 Analytics to track most-used bookmarks
• 🔄 Import/Export from popular bookmark managers
• 🌐 Web interface for visual bookmark management
• 🏷️ Tag system for more flexible organization

🤝 Join the Journey

This project is open-source and ready for contributors! Whether you're interested in:

• Adding new features 🆕
• Improving documentation 📖
• Fixing bugs 🐛
• Sharing feedback 💬

Check out the GitHub repository and let's build something amazing together! 🚀

🎉 Final Thoughts

Building this bookmark manager taught me that the future of productivity tools isn't just about better UIs - it's about better integrations. When your tools can talk to each other naturally, magic happens! ✨

The Model Context Protocol is opening doors to a new era of AI-integrated development tools. This bookmark manager is just the beginning.🤔

Ready to revolutionize your bookmark management?
⭐ Star the repo, give it a try, and let me know what you think!

Connect with me:

• 🐙 GitHub: @infinitepi-io
• 💼 LinkedIn: Satish Tripathi
• 🌐 Blog: infinitepi-io.github.io
• 🐳 Docker Hub: mindriftfall2infinitepiio/mcp

Happy bookmarking! 🔖

Read more of this story at Slashdot.