TDD = bra design?

TDD = bra design?KJETIL KLAUSSEN

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GreenRefactor

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GreenRefactor

1. Skriv test

2. Sjekk at testen feiler

3. Implementer

4. Sjekk at alle tester er OK

6. Sjekk at alle tester er OK

5. Forbedring

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Vil TDD føre til

bedre design?

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Bedre enn hva?

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OpsTesting

KodingDesign

AnalyseKravspek

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GreenRefactor

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Debugging

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KodeDebugging

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Hva er bra design?

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Man må vite hva bra design er hvis man ønsker å skape det

- Kjetils postulat

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Prinsipper

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Patterns

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Prinsipper Domain-driven design (DDD) Single responsibility (SRP) Open/closed (OCP) Liskov’s substitution (LSP) Interface segregation (ISP) Dependency inversion (DIP) Law of Demeter (LoD) Tell, don’t ask Principle of least surprise (PoLP)

Design by Contract Feature envy High cohesion / low coupling 4 rules of simple design (4RoSD) Balanced abstraction Separation of concerns (SoC) You ain’t gonna need it (YAGNI) Don’t repeat yourself (DRY) Keep it simple stupid (KISS)

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Design Patterns Factory Singelton Monostate Prototype Adapter Bridge Composite Decorator Facade

Flyweight Proxy Command Mediator Memento Null Object Specification State Strategy

Template method Visitor Repository Aggregate Entity Value Object Model View Controller Model View Presenter

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Architectural Patterns Structure

◦ Component-based (CBSE)

◦ Monolithic◦ Layered◦ Pipes and filters

Shared Memory◦ Data-centric◦ Blackboard◦ Rule-based

Messaging◦ Event-driven (EDA)◦ Pub-sub◦ Message-oriented

Adaptable◦ Plug-ins◦ Microkernel◦ Reflection◦ DSL

Distributed◦ Client-server◦ Shared nothing (SN)◦ Space-based◦ Object request broker◦ Peer-to-peer◦ REST◦ Service-oriented◦ Microservices

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"You can't do good design without experience. When less experienced people do TDD they typically don't refactor enough, leading to sub-optimal designs"