Unit Test Boundary Conditions

Covers the boundary conditions that break production code but somehow never make it into your test suite until they do. Handles integer min/max values, overflow detection with Math.addExact, null and empty strings, collection edge cases (empty, single, many), floating-point precision with tolerance-based assertions, and array index boundaries. Uses JUnit 5 parameterized tests to run multiple boundary values efficiently. The examples are thorough, showing both the happy path at boundaries and the exceptions you should expect. The iterative approach is smart: when a boundary test fails, use that to discover what other edges you missed. If you're tired of production bugs from zero-length arrays or MAX_VALUE plus one, this gives you the patterns to catch them in tests first.