Structural Testing

Def: judging test suite thoroughness based on the structure of the program itself

• Also known as white-box testing
• Distinguish from functional testing (black-box testing)
  • structural testing is still testing product functionality against its specification
  • only the measure of thoroughness has changed

Why need structural testing:

• Executing all control flow elements does not guarantee finding all faults
• Increase confidence in thoroughness of testing

Practical use:

• Firstly create functional test suite
• Then measure structural coverage to identify see what is missing

Statement testing & Branch testing

Statement testing:

• Adequacy criterion: each statement must be executed at least once
• Rationale: a fault in a statement can only be revealed by executing the faulty statement

Branch testing:

• Adequacy criterion: each branch (edge in the CFG) must be executed at least once

Comparison:

Traversing all edges of a graph causes all nodes to be visited, so we have:

• Test suites that satisfy the branch adequacy criterion for a program P also satisfy the statement adequacy criterion for the same program
• A statement-adequate (or node-adequate) test suite may not be branch-adequate (edge-adequate)