CPSA Software Design Principles 3

Question 1

Which statement BEST describes the Open/Closed Principle?

Accepted Answer

Software entities should be open for extension but closed for modification

Answer

The Open/Closed Principle states that software entities should be open for extension (new behavior can be added) but closed for modification (existing code is not changed).

Question 2

A designer uses inheritance but the subclass cannot be used wherever the parent class is expected without breaking behavior. Which principle is violated?

Accepted Answer

Liskov Substitution Principle

Answer

The Liskov Substitution Principle requires that subtype objects must be substitutable for their supertype objects without altering program correctness.

Question 3

What is the PRIMARY benefit of applying the DRY (Don't Repeat Yourself) principle?

Accepted Answer

Reduced risk of inconsistency when changing logic in one place

Answer

DRY reduces duplication so that when logic must change, it is updated in exactly one place, eliminating the risk of inconsistent copies.

Question 4

Which design heuristic does the statement 'You should not design for needs that do not yet exist' represent?

Accepted Answer

YAGNI (You Aren't Gonna Need It)

Answer

YAGNI advises against implementing functionality until it is actually needed, avoiding unnecessary complexity and speculative design.

Question 5

In layered architecture, what design principle is enforced when higher layers only interact with the layer directly below them?

Accepted Answer

Layer isolation / strict layering

Answer

Strict layering enforces that each layer only communicates with the adjacent lower layer, maintaining clear boundaries and reducing coupling across layers.

CPSA Exam Practice Test

CPSA Exam Practice Test

CPSA Software Design Principles 3