White-box technique-Statement Coverage : ISTQB Foundation Level

Question

I have found the following questions regarding statement coverage.

Minimum Test Required for Statement Coverage:

1. Disc = 0
2. Order-qty = 0
3. Read Order-qty
4. If Order-qty >=20 then
   1. Disc = 0.05
   2. If Order-qty >=100 then
      1. Disc =0.1
   3. End if
5. End if

In my opinion, we need 2 statement coverage. But the correct answer is 1 statement based on many websites.

I don't understand why only one statement coverage is needed.

Answer 1

The reason you only need one statement is in the initial conditions, specifically

Order-qty = 0

With an order quantity of 0 there is only one possible pass through the logic listed: the first if statement, Order-qty >=20 evaluates to false, making the next statement number 5, the End if.

Different starting conditions could potentially require different coverage, but for any value of Order-qty between 0 and 19 inclusive, only one statement is needed.