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.

skills.sh installs: 4.2K
GitHub stars: 369
last updated: Aug 21, 2026

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Install

$ npx -y skills add giuseppe-trisciuoglio/developer-kit --skill unit-test-boundary-conditions --agent claude-code

Installs into .claude/skills of the current project.

Files

Unit Testing Boundary Conditions and Edge Cases

Overview

Systematic patterns for testing boundary conditions, corner cases, and limit values in Java using JUnit 5. Covers numeric boundaries, string edge cases, collection states, floating-point precision, date/time limits, and off-by-one scenarios.