Boundary Value Analysis
Master boundary value analysis to test edge cases and boundary conditions. This is a foundational concept in quality assurance and test automation that professional developers rely on daily. The explanations below are written to be beginner-friendly while covering the depth and nuance that comes from real-world Software Testing experience. Take your time with each section and practice the examples
40 min•By Priygop Team•Last updated: Feb 2026
Boundary Value Analysis Principles
- Focus on boundary values of input ranges — a critical concept in quality assurance and test automation that you will use frequently in real projects
- Test values just inside and outside boundaries — a critical concept in quality assurance and test automation that you will use frequently in real projects
- Most errors occur at boundaries — a critical concept in quality assurance and test automation that you will use frequently in real projects
- Test minimum, maximum, and edge values — a critical concept in quality assurance and test automation that you will use frequently in real projects
- Apply to both valid and invalid ranges — a critical concept in quality assurance and test automation that you will use frequently in real projects
Boundary Value Examples
Example
// Example: Age validation (18-65)
function testAgeBoundaries() {
// Valid range: 18-65
// Test boundaries: 17, 18, 19, 64, 65, 66
// Just below minimum (invalid)
expect(validateAge(17)).toBe(false);
// Minimum valid
expect(validateAge(18)).toBe(true);
// Just above minimum (valid)
expect(validateAge(19)).toBe(true);
// Just below maximum (valid)
expect(validateAge(64)).toBe(true);
// Maximum valid
expect(validateAge(65)).toBe(true);
// Just above maximum (invalid)
expect(validateAge(66)).toBe(false);
}
// Example: Password length (8-20 characters)
function testPasswordBoundaries() {
// Valid range: 8-20 characters
// Test boundaries: 7, 8, 9, 19, 20, 21
// Just below minimum (invalid)
expect(validatePassword("1234567")).toBe(false); // 7 chars
// Minimum valid
expect(validatePassword("12345678")).toBe(true); // 8 chars
// Just above minimum (valid)
expect(validatePassword("123456789")).toBe(true); // 9 chars
// Just below maximum (valid)
expect(validatePassword("1234567890123456789")).toBe(true); // 19 chars
// Maximum valid
expect(validatePassword("12345678901234567890")).toBe(true); // 20 chars
// Just above maximum (invalid)
expect(validatePassword("123456789012345678901")).toBe(false); // 21 chars
}
// Example: Array bounds
function testArrayBoundaries() {
const arr = [1, 2, 3, 4, 5]; // Length: 5, valid indices: 0-4
// Just below minimum (invalid)
expect(() => arr[-1]).toThrow();
// Minimum valid
expect(arr[0]).toBe(1);
// Just above minimum (valid)
expect(arr[1]).toBe(2);
// Just below maximum (valid)
expect(arr[3]).toBe(4);
// Maximum valid
expect(arr[4]).toBe(5);
// Just above maximum (invalid)
expect(arr[5]).toBeUndefined();
}