Mathematical Singularities & Infinite Loops

This module explores a class of date-related bugs that crash programs or freeze them entirely — not through incorrect output, but through mathematically undefined operations and runaway loops. When dates are used in arithmetic calculations, edge cases like zero-length intervals can trigger division by zero errors. When iteration logic relies on date progression, a single off-by-one mistake can produce an infinite loop that pegs the CPU at 100% until the process is killed.

QA testers who understand these failure modes can craft inputs that expose them before they reach production. You will learn how division-by-zero manifests differently across languages (ArithmeticException in Java, NaN in JavaScript, Infinity in Python), how to recognize the CPU signature of a runaway date loop, and how to safely test iterative date algorithms without waiting for a timeout to trigger.

The module also covers recurring event generation — a deceptively complex domain where business rules like "every month on the 31st" collide with calendar reality. Testing recurrence engines requires methodical boundary work: what happens on the last day of each month, across year boundaries, and during daylight saving transitions?