Introduction to Software Testing Chapter 2 4 Graph Coverage for Design Elements Paul Ammann Jeff Offutt www introsoftwaretesting com This version is abbreviated Data flow coverage is omitted OO Software and Designs Emphasis on modularity and reuse puts complexity in the design connections Testing design relationships is more important than before Graphs are based on the connections among the software components Connections are dependency relations also called couplings Introduction to Software Testing Ch 2 www introsoftwaretesting com Ammann Offutt 2 Call Graph The most common graph for structural design testing Nodes Units in Java methods Edges Calls to units A B Node coverage call every unit at least once method coverage C E D F Example call graph Edge coverage execute every call at least once call coverage Introduction to Software Testing Ch 2 www introsoftwaretesting com 3 Ammann Offutt Call Graphs on Classes Node and edge coverage of class call graphs often do not work very well Individual methods might not call each other at all Class stack public void push Object o public Object pop public boolean isEmpty Object o push pop isEmpty Other types of testing are needed do not use graph criteria Introduction to Software Testing Ch 2 www introsoftwaretesting com Ammann Offutt 4 Inheritance Polymorphism Caution Ideas are preliminary and not widely used A Classes are not executable so this graph is not directly testable B We need objects A D C a Example inheritance hierarchy graph objects B b C c Introduction to Software Testing Ch 2 www introsoftwaretesting com D d What is coverage on this graph Ammann Offutt 5 Coverage on Inheritance Graph Create an object for each class This seems weak because there is no execution Create an object for each class and apply call coverage OO Call Coverage TR contains each reachable node in the call graph of an object instantiated for each class in the class hierarchy OO Object Call Coverage TR contains each reachable node in the call graph of every object instantiated for each class in the class hierarchy probably more appropriate Data flow is Data flow not covered in undergraduate course Introduction to Software Testing Ch 2 www introsoftwaretesting com Ammann Offutt 6 Summary Applying structural coverage techniques non data flow to these graphs is easy The hard part is the data flow Variables are defined in one method passed as a parameter then used in a called method Class variables are defined in one method and used in another Values are transferred to another class Values are sent by message to another web component Introduction to Software Testing Ch 2 www introsoftwaretesting com Ammann Offutt 7