/mint

Boundary Value Strategy

Purpose: Systematic boundary value and edge case data generation. Read when: Identifying edge cases for comprehensive test data coverage.

Boundary Value Analysis (BVA) Matrix

String Fields

Numeric Fields

Date/Time Fields

Array/Collection Fields

Nullable / Optional Fields

Combinatorial Edge Cases

Pairwise Boundary Combination

Generate combinations that cover each pair of boundary values at least once.

function* boundaryPairs<T>(boundaries: Record<string, T[]>) {
  const keys = Object.keys(boundaries);
  for (let i = 0; i < keys.length; i++) {
    for (let j = i + 1; j < keys.length; j++) {
      for (const vi of boundaries[keys[i]]) {
        for (const vj of boundaries[keys[j]]) {
          yield { [keys[i]]: vi, [keys[j]]: vj };
        }
      }
    }
  }
}

// Usage
const userBoundaries = {
  name: ['', 'a'.repeat(255), '日本語', '<script>'],
  age: [0, -1, 150, NaN],
  email: ['', 'invalid', 'a@b.c', 'a'.repeat(254) + '@x.co'],
};

Property-Based Testing Generators

Arbitraries for Common Types

// fast-check arbitraries
import fc from 'fast-check';

const userArbitrary = fc.record({
  name: fc.string({ minLength: 1, maxLength: 255 }),
  email: fc.emailAddress(),
  age: fc.integer({ min: 0, max: 150 }),
  role: fc.constantFrom('user', 'admin', 'moderator'),
  tags: fc.array(fc.string(), { maxLength: 10 }),
});

fc.assert(
  fc.property(userArbitrary, (user) => {
    const result = validateUser(user);
    return result.isValid || result.errors.length > 0;
  })
);

# Hypothesis strategies
from hypothesis import given, strategies as st

@given(
    name=st.text(min_size=1, max_size=255),
    age=st.integers(min_value=0, max_value=150),
    email=st.emails(),
)
def test_user_creation(name, age, email):
    user = create_user(name=name, age=age, email=email)
    assert user.id is not None

Domain-Specific Boundaries

E-Commerce

Authentication

Financial