-code With Mosh- Mastering Javascript Unit Testing Now

Leo turned to Sarah. "I broke the code on purpose. The tests found it in 0.3 seconds."

test('calculate total price for two items', () => { // Arrange const cart = [{ price: 10 }, { price: 20 }]; // Act const result = calculateTotal(cart); // Assert expect(result).toBe(30); }); Leo typed along. For the first time, he ran npm test and saw that beautiful green checkmark. Passed. -Code With Mosh- Mastering JavaScript Unit Testing

She started laughing. "Best thirty dollars this company ever spent." Six months later, Leo wasn't a firefighter anymore. He was the team's testing evangelist. New hires came to him with shaky pull requests, and he'd say the same thing Mosh said to him: Leo turned to Sarah

Because Leo finally understood: writing tests wasn't about proving his code worked today. It was about having the courage to change it tomorrow. For the first time, he ran npm test