Legacy Code Safety

"Changing untested code is like performing surgery blindfolded."

DANGER: The Risk of Modifying Untested Code

Modifying code without tests is one of the HIGHEST-RISK activities in software development.

When you change untested code:

• You CANNOT know what behaviors you're breaking
• You have NO safety net to catch mistakes
• You're relying on hope instead of evidence
• You're creating technical debt on top of technical debt

In dynamically-typed languages (Python, JavaScript, Ruby, PHP), this risk is EXPONENTIALLY higher: