Why Working Code Isn’t Always Safe Code

Huseyn Ashurlu

7 min read10 hours ago

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The payment button works. The API responds. Everything passes testing. But what happens when the user does something you didn’t expect?

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Imagine a simple payment page.

A user enters an amount, selects a payment method, and clicks Pay .

The request goes to the backend.

The payment succeeds.

A confirmation message appears.

Everything works exactly as expected.

The developer tests it again.

Still works.

The feature gets approved.

Now imagine the same page in a slightly different situation.

The user clicks Pay , but nothing appears to happen.

Maybe the internet is slow.…