The document discusses Test Driven Development (TDD) and provides details on: 1. The three rules of TDD which require writing failing tests first and only producing minimal production code to pass each test. 2. Refactoring as an important part of TDD to refine code design as new tests are added and production code is incremented. 3. Code smells which are surface indications of deeper problems like duplicated code, long methods, and large classes that should be refactored.

1. Test Driven DevelopmentTest Driven Development
Part 2
Gamal ShaabanGamal Shaaban
International Centers
Orange Labs Cairo
Mobile Applications & Software Development

2. 2 Orange restricted

3. 3 Orange restricted
Session-2Session-2
3
• The Three Rules Of TDD
• Legacy Code & Refactoring
• Code Smells
• Coupling And Cohesion
• Continues Integration

4. 4 Orange restricted
THE THREE
RULES OF TDD 1. You are not allowed to write any production
code unless it is to make a failing unit test pass.
2. You are not allowed to write any more of a unit
test than is sufficient to fail; and compilation
failures are failures.
3. You are not allowed to write any more
production code than is sufficient to pass the
one failing unit test.
 http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd
4

5. 5 Orange restricted
RefactoringRefactoring  Refactoring is one of the most important parts
of TDD, which means you need to refine the
code design as you add new tests.
 Refactoring should be done consistently as
you increment the software, adding tests and
production code.
 Make code easier to maintain in the future
 Use IDE when possible to do refactoring.
 Refactor Without Fear.
5

6. 6 Orange restricted
Code SmellsCode Smells
A code smell is a surface indication that usually corresponds to
a deeper problem in the system.
Martin FowlerMartin Fowler
http://martinfowler.com/bliki/CodeSmell.html
6

7. 7 Orange restricted
Smells To BeSmells To Be
RefactoredRefactored
1.Duplicated Code
2.Long Method
3.Large Class
4.Long Parameter List
5.Divergent Change
6.Lazy Class
7.Speculative Generality
8.Temporary Field
9.Data Class
10.Refused Bequest
11.Comments
12.MiddleMan

8. 8 Orange restricted
COUPLING ANDCOUPLING AND
COHESIONCOHESION
 Maximize internal interaction
(cohesion)
• easier to understand
• easier to test
 Minimize external interaction
(coupling)
• can be used independently
• easier to test
• easier to replace
• easier to understand
8

9. 9 Orange restricted
9
Degree of dependence
among components
No dependencies Loosely coupled-some dependencies
Highly coupled-many dependencies

10. 10 Orange restricted

11. 11 Orange restricted
CONTINUES INTEGRATION

12. 12 Orange restricted
• Teams integrate their work multiple times
per day.
• Each integration is verified by an
automated build
• Significantly reduces integration problems
• Develop cohesive software more rapidly
Source: Martin Fowler

13. 13 Orange restricted
Five Principles of Continuous Integration
• Environments based on stability
• Maintain a code repository
• Commit frequently and build every commit
• Make the build self-testing
• Store every build
13

14. 14 Orange restrictedOrange presentation
Questions?

15. thanks