2. Software Design Patterns in Test Automation

3. Table of Content Objectives What are Design Patterns?
Design Pattern and Design Principle - what's the difference?
Principles
KISS
Don’t Repeat Yourself.
5. Patterns
Multi-layered test solution
Facade
Chaining
Template Method

4. Objectives
Present the concepts of „design pattern” & „design principle”
Show why these concepts are important
Describe chosen patterns & principles.
All presented patterns have examples in C# but can be used with most Object-Oriented Languages
Target Audience: Testers who are writing automated tests and want to dive deeper into programing world.

5. Software Design Pattern
General reusable solution to a commonly occuring problem within given context
Object-Oriented Desgin Patterns typically show relationships between classes and objects without specifing theirs final application.
(a pattern) „describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same ay twice„- Christopher Alexander

6. Pattern vs Principle
Software Design Principle - Set of Guidelines that helps to avoid bad design and unmaintainable code.
„Design principles are the desirable goals that one aims to achieve. Design patterns are tools one can use to realize those goals. ” – E Arimitage

7. KISS
Keep it simple stupid.
(KISS)

8. KISS – Example

9. KISS – Example

10. Solution

11. DRY
Don’t Repeat yourself
(DRY)

12. DRY - Example

13. Solution

14. Time for Patterns

15. Multi Layered Test Solution
Strategy
Multi Layered Test Solution

16. Overview

17. Example

18. Pros & Cons Low maintenance effort and time Enhanced code reusability
Structured codebase which is easy to fix and extend
Improved communication
Complexity
Time invested during creation
Experience

19. Facade
Facade

20. Facade provides an unified interface in subsystem.
Facade – description
Facade provides an unified interface in subsystem.
Defines a higher-level interface that makes the subsystem easier to use.

21. Facade – UML

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Facade - Test Case
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23. Facade – Before

24. Facade –After

25. Facade – Front Facade Implementation

26. Less time spent on writing new test cases Easier maintenance.
Pros & Cons
Less time spent on writing new test cases
Easier maintenance.
Test is harder to debug if it fails in ‚unexpected’ way.
Test is unreadable – if treated as an Unit Test.

27. Methods Chaining

28. Methods Chaining- Example

29. Chaining – methods difference

30. Pros & Cons Helps when writing tests Clean Code & Readability
Person can’t see what object is returned
Chain breaks

31. Template Method

32. Template Method– description
Define the skeleton of an algorithm in an operation, deferring some steps to subclasses.
Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.

33. Template Method– UML

34. Template Method -Test Cases
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35. Template Method - Example

36. Template Method - Example

37. Quite hard to understand To understand what going on in test
Pros & Cons
Avoiding God Class
Modularization
Quite hard to understand
To understand what going on in test
‚little digging’ is neccesary

38. Design patterns are more like guidelines
Summary
Design patterns are more like guidelines
Patterns can be bad if used in wrong context
Anybody can use them
Do not force patterns into your code!!!
Anti-Patterns

39. Head First Design Patterns – O’Reily Media
Bibliography
Head First Design Patterns – O’Reily Media
Design Patterns: Elements of Reusable
Object-Oriented Software

40. Questions?

41. Contact Us

42. Thank you for your attention
Krzysztof Wilczyński & Maciej Wyrodek