🏦 Bridging Development and QA: My Journey from Code Design to Manual Testing Mastery

How I Learned Testable Design by Breaking My Own ATM System: ** It Started With a "Working" System** I built an ATM simulator. It worked. At least, that's what I thought. From a developer's perspective, everything looked fine: Log in ✔ Check balance ✔ Deposit and withdraw ✔ Transfer funds ✔ Then I asked a simple question: How do I know this system actually works correctly? That question changed everything. ** The Illusion of "It Works"** At first, I was testing informally: Try a valid input → works Try another valid input → works I felt confident. But I wasn't testing. I was confirming my own assumptions. ** The Turning Point: When I Tried to Test Properly** I decided to approach my own system like a QA engineer. Not casually, but systematically. That's when I realised something uncomfortable: I didn't actually have clearly defined expected behaviour. ** From Code to QA: Where Everything Became Real** I created a separate repository dedicated to manual testing. Not random testing, but