testing Software Testing Techniques - Boundary Value Analysis Progressive discount


The rule

Another common case we usually find and where it is useful to apply this technique are progressive rates based on values.

An e-commerce has an offer that is like:

  • 10% off for orders above US$ 80.00
  • 15% off for orders above US$ 150.00
  • 25% off for orders above US$ 200.00

How to apply the technique

Rule of thumb: we always will pick the two sides of each boundary. For this case we will need to test with orders with the following values:

  • US$ 79.99 (no discount)
  • US$ 80.00 (10% off)
  • US$ 149.99 (10% off)
  • US$ 150.00 (15% off)
  • US$ 199.99 (15% off)
  • US$ 200.00 (25% off)

This is enough to cover all intervals with a great confidence level.