JNTU MCA 2017 SOFTWARE TESTING METHODOLOGIES Previous Question Paper (August 2017 - R09)

Path Predicates are the set of boolean conditions that must be satisfied for a specific path through a program to be traversed. Each decision point (such as an if-statement or loop condition) along a path imposes a constraint on the input variables. A path is defined by the sequence of branches taken; the path predicate is the logical conjunction of all individual branch predicates along that path. If the path predicate is satisfiable, there exists at least one set of input data that will cause that path to be executed.

Achievable Paths are paths for which the path predicate is consistent and satisfiable. A path is considered unachievable if the path predicate is a contradiction (e.g., x > 5 AND x < 2), meaning no input data can satisfy the conditions required to traverse that specific sequence of branches. Identifying unachievable paths is crucial in software testing because they represent dead code or unreachable logic that cannot be exercised during testing, regardless of the input.

Path Instrumentation is a technique used to monitor and verify the execution of paths during testing. It involves inserting additional code (probes or counters) into the source program to track which branches or paths are taken during execution. Key aspects include:

• Probe Insertion: Strategic placement of logging statements or flags at entry and exit points of basic blocks or decision nodes.
• Data Collection: Capturing the sequence of executed nodes to reconstruct the actual path taken by the program under test.
• Verification: Comparing the actual execution path against the expected path to validate program logic and ensure test coverage requirements are met.
• Overhead Management: Minimizing the performance impact of instrumentation while ensuring sufficient data is collected to identify path-related defects.