# Your Job Isn’t Just Writing Code. It’s Proving It Works

Software development isn’t about churning out lines of code and *hoping* they work. Anyone can generate code, even AI does that now. What *separates the pros from the amateurs* is this:

## ✅ Your job is this: **Deliver code *you have personally verified works***

No ifs, no maybes, no “let reviewers find the bugs.”

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## 😬 The Problem Today

We’ve all seen it: a huge AI-generated pull request lands with no evidence that it actually works. Someone else, usually a reviewer or maintainer, has to chase down bugs, figure out if it even *runs*, and fix it. That’s not teamwork, that’s dumping your mess on someone else.

That *used to* be forgivable. Today? There’s no excuse.

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## 🧠 Real Software Engineering = Proof

A real engineer doesn’t just *hope* code works. They *prove* it. There are **two essential steps** every time:

### 1️⃣ **Manual testing first**

You must see your code do the right thing yourself.

* Run it
    
* Try it
    
* Break it  
    If you haven’t seen it actually work with your own eyes, it *might as well* be imaginary.
    

A smart trick: capture a terminal log or short screen recording that shows your change working and include that in your pull request.

### 2️⃣ **Then write an automated test**

Tests are your safety net, they prove your change still works tomorrow, next month, and after someone else touches it.  
Modern tools make this easier than ever. Skip this only if you *love* bugs.

**Manual testing + automated tests = Proof.**

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## 🤖 Even If AI Wrote the Code

Yes, modern coding assistants like Claude Code and Codex CLI can write and test code for you. But that doesn’t mean you can trust them blindly.

You still need to:

* Teach the tool to *show* it tested the code.
    
* Understand the test results.
    
* Add proper automated tests to your repo yourself.
    

In other words: **AI assists, you’re responsible.**

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## 💡 Why This Matters

Submitting unproven code:

* Wastes reviewers’ time
    
* Introduces hidden bugs
    
* Shifts the real work to someone else
    

Proving your code works:

* Saves time
    
* Builds trust
    
* Makes you a stronger engineer
    

It’s not optional. It’s the **real definition of professional software development** in an AI-augmented world.

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## 🔥 TL;DR: The New Rules of Quality Code

✔ Run your code yourself  
✔ Show it works  
✔ Add automated tests  
✔ Don’t submit anything unless it’s proven

Treat your evidence of working code like gold. Anyone can write lines *you prove results.*

Source: [https://simonwillison.net/2025/Dec/18/code-proven-to-work/](https://simonwillison.net/2025/Dec/18/code-proven-to-work/)