Test Driven Test Driven Development Development Part 2 Gamal Shaaban Gamal Shaaban International Centers Orange Labs Cairo Mobile Applications & Software Development
Test Driven Development Part 2
Nov 01, 2014
The Three Rules Of TDD
Legacy Code & Refactoring
Code Smells
Coupling And Cohesion
Continues Integration
THE THREE RULES OF TDD
You are not allowed to write any production code unless it is to make a failing unit test pass.
You are not allowed to write any more of a unit test than is sufficient to fail; and compilation failures are failures.
You are not allowed to write any more production code than is sufficient to pass the one failing unit test.
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.
A code smell is a surface indication that usually corresponds to a deeper problem in the system.
Duplicated Code
Long Method
Large Class
Long Parameter List
Divergent Change
Lazy Class
Speculative Generality
Temporary Field
Data Class
Refused Bequest
Comments
MiddleMan
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
Legacy Code & Refactoring
Code Smells
Coupling And Cohesion
Continues Integration
THE THREE RULES OF TDD
You are not allowed to write any production code unless it is to make a failing unit test pass.
You are not allowed to write any more of a unit test than is sufficient to fail; and compilation failures are failures.
You are not allowed to write any more production code than is sufficient to pass the one failing unit test.
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.
A code smell is a surface indication that usually corresponds to a deeper problem in the system.
Duplicated Code
Long Method
Large Class
Long Parameter List
Divergent Change
Lazy Class
Speculative Generality
Temporary Field
Data Class
Refused Bequest
Comments
MiddleMan
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
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Transcript
Test Driven Test Driven DevelopmentDevelopment
Part 2Gamal Shaaban Gamal Shaaban International CentersOrange Labs CairoMobile Applications & Software Development
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Session-2Session-2
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• The Three Rules Of TDD• Legacy Code & Refactoring• Code Smells• Coupling And Cohesion• Continues Integration
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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
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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.
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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
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Smells To Be Smells 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
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COUPLING AND COUPLING 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
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Degree of dependence among components
No dependencies Loosely coupled-some dependencies
Highly coupled-many dependencies
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CONTINUES INTEGRATION
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• Teams integrate their work multiple timesper day.
• Each integration is verified by an automated build
• Significantly reduces integration problems
• Develop cohesive software more rapidly
Source: Martin Fowler
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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
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Questions?
thanks
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