Testing Extensible Design Patterns in OO Frameworks through Scenario TemplatesD.S. Sanders

Software Verification & Validation

Design Patterns

Proven architectures for constructing flexible and maintainable software

Promotes design reuse Language independent Neither classes nor objects

Origins & Progenitors

The “Gang of Four” Eric Gamma Richard Helm Ralph Johnson John Vlissides

Collectively penned “Design Patterns”: Elements of Reusable OO Software

Written between 1991-1994; released ‘95

Creational Patterns

Abstract Factory* Factory Method* Builder Prototype Singleton

Structural Patterns

Adapter Bridge Composite Decorator Façade Flyweight Visitor

Behavioral Patterns

Chain of Responsibility Command Interpreter Iterator Mediator

Momento Observer State Strategy* Template Method Visitor*

Post Gang of Four Patterns

Architectural Patterns Model – View – Controller

Concurrency Patterns Single Threaded Execution Guarded Suspension Balking Read / Write Lock Two Phase Termination

Memory Lane – Comp 110

Dynamic Typing Some or all type checking done at runtime

More memory lane – Comp 110 Dynamic Binding

Determining at runtime the appropriate method to call

Pattern Categorization - Redux Static

Does not allow for easy extension Behavior does not change after compile time Easier to test

Extensible Allows functionality of the app to change Adds new classes to the system Some of the classes loaded at runtime

Factory Method Pattern

Factory Method Example

Factory Method Example

Strategy Pattern

Strategy Pattern Example

So much testing…so little time Scenario Based Testing Method Sequence Specification (MtSS) Message Sequence Specification (MgSS) Message Framework Specification (MfSS)

The Bank

MtSS of Account Class and MgSS of Method Withdraw

Message Framework Sequence Specs

Test Cases

MfSS Slicing Partition Testing

Object Types Number of / Groups of Objects Object Input Space

More Memory Lane – Comp 380 Stress Testing Boundary Testing Negative Testing Random Testing

Compensating for Extensibility Testing Dynamic Typing Testing Dynamic Binding Testing Extensibility

Testing Results

Conclusion

Testing Extensible Design Patterns is difficult MfSS will generate scenario templates which

lead to test cases Use in Industry seems limited Source Code Credit

Kathy Sierra, Bert Bates (Factory, Strategy) Collegeboard.org (GridWorld Case Study)