Is there a method containing a division by zero fault at least two branches such that (1) it is possible to create a test suite that achieves 100% path coverage and reveals the fault, and (2) every possible test suite that achieves 100% branch coverage does not reveal the fault?
Answer (1)
This question involves understanding path coverage and branch coverage in software testing, and how faults can be revealed through these methods.
Software Testing Concepts :
Path Coverage is a measure used in software testing to ensure that all possible paths through a given part of the code are executed at least once. It involves testing complex logical conditions to ensure that all feasible paths (including loops) are executed, potentially uncovering bugs that are not caught through other methods.
Branch Coverage , on the other hand, involves testing each possible branch of every decision or control structure within the code (like 'if' or 'while' statements). It ensures that each branch is executed at least once during the tests.
The Problem :
Path Coverage Revealing the Fault : It is possible to create a test suite achieving 100% path coverage that reveals a division by zero fault. This occurs because path coverage, which explores all possible execution paths, ensures that any logical path leading to a division by zero error is executed, which then reveals the fault.
Branch Coverage Not Revealing the Fault : However, 100% branch coverage might not reveal the division by zero fault, as it does not guarantee that all logical paths are executed, only that each branch is reached. It may cover the decision branches without exploring all combinations of input that lead to the execution of the actual divide operation.
Example :
Consider the following pseudo-code:
if (condition1) result = 10 / x else result = 1
With Path Coverage : A test suite would need to try inputs that cause condition1 to be true and explore possible values for x, including 0, which would reveal the division by zero fault.
With Branch Coverage : A test suite might only verify that both branches (when condition1 is true and false) are covered, but it might not include the specific test where x is zero, so the fault is not revealed.
Thus, this example demonstrates that achieving 100% path coverage has the potential to reveal faults like division by zero, which might be missed with branch coverage alone.
