Boundary value testing is used to check the behavior of the system at the boundaries of input ranges. Time zones often have critical boundaries, such as the change from one day to the next or the switch between standard time and daylight saving time.

Boundary Value Analysis: Tests the values at the edges of equivalence classes, which in the context of time zones could include:

Transition points between time zones

Daylight saving time changes

Leap years and the end/start of months

Efficiency: Testing boundaries is typically more efficient than testing all possible values, especially when dealing with large ranges like time zones.

Application: Ensures that the software handles edge cases correctly, such as the change from 11:59 PM in one time zone to 12:00 AM in another.