Programmers Stack Exchange is a question and answer site for professional programmers interested in conceptual questions about software development. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have been studying condition coverage for last few days. In a book "The Art of Software Testing" they highlight that it does not assure decision coverage, because for example

IF(A && B)

A=True, B=false and A=False,B=True satisfies the condition coverage but the decision is always False.

I wonder, how can this satisfy the coverage? The True value of B will actually never be tested because of short circuiting so how it can satisfy the coverage?

share|improve this question

Condition coverage is about testing that any operands which are part of the if expression can be evaluated to both true and false without issues. In this type of coverage, you don't care about what would be executed inside the braces, nor about the result of the operand used in a condition.

Take the following code:

bool a = ...;
bool b = ...;
if (a && b)

Condition coverage of this code would require to test:

  • a for both true and false, and:
  • b for both true and false.

In languages which require both operands to evaluate in a logical operation, condition coverage of the code above is satisfied with:

a = true; b = false
a = false; b = true

This is what is illustrated in your question.

Some languages evaluate the second operand of a logical AND only if the first operand is true (or evaluate the second operand of OR only if the first operand evaluates to false). In this case, three tests are required instead of two:

a = true; b = true
a = true; b = false
a = false

As you can note, we don't care about the value of b in the third test, since the program will never compute it when a is false.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.