ISTQB Certified Tester Foundation Level (CTFL 2018) — Question 31

A supermarket rewards its customers with discounts on certain products depending on how much the customer spends over a twelve-month period. The discounts are:

• 5% discount – once £500 has been spent.
• 10% discount – once a further £500 has been spent.
• 15% discount – once a further £1000 has been spent.
• 20% discount – once a further £2000 has been spent.

The following test cases have been written:

TC1 – £500 spent -

TC2 – £2000 spent -

How many more test cases must be written to achieve 100% 2-point boundary value analysis for the discount scheme?

Answer options

• A. 4.
• B. 6.
• C. 7.
• D. 8.

Correct answer: B

Explanation

The correct answer is B, as each discount threshold represents a boundary that must be tested. Since there are four discount levels and two test cases already provided, additional cases are needed for the boundaries between £500 and £1000 as well as between £1000 and £2000, resulting in a total of six necessary test cases to cover all boundaries.