-code With Mosh- Mastering Javascript Unit Testing May 2026

His boss, Sarah, would inevitably Slack him: “Hey Leo, the checkout button broke again. Also, the user profile picture is showing up on the invoice page.”

Mosh started simple.

It felt… clean. The next lesson hit him like a truck. Mosh introduced Test-Driven Development (TDD) . -Code With Mosh- Mastering JavaScript Unit Testing

Because Leo finally understood: writing tests wasn't about proving his code worked today. It was about having the courage to change it tomorrow. His boss, Sarah, would inevitably Slack him: “Hey

And that made him a real engineer.