Fix my TDD Patterns for efficient Tests

Christian Fischer Software Engineering Coach http://agiledojo.de @agiledojo

Christian Fischer TDD in a Nutshell Test Implementation Refactoring

Christian Fischer Simple, but not easy

Christian Fischer Password Validator Kata boolean validate(String password) A password it valid, when it has • at least 6 characters • at least one upper case letter • at least one lower case letter • at least one special character

Christian Fischer The Test List Valid password „aBc_de -> true Less than minimum characters „aBc_de“ -> false No upper case „ab_cde“ -> false No lower case „ABC_DE“ -> false No special character „aBcxde“ -> false 1 Analyse the problem 2 find simple examples for each equivalence class 3 add to list any time, but don‘t interrrupt cycle from Kent Beck

Christian Fischer Test Storming • Swarm Intelligence • Time boxing • Integration in Refinement and Planning or 3-Amigo-Session

Christian Fischer Test Path • from simple to complex • start with happy path • use git to rewind

Christian Fischer ZOMBIES Simple Scenarios Simple Solutions Zero One Many Boundaries Behavior Interfaces Exercise Exceptions from James Grenning

Christian Fischer Transformation Priority Premise {} --> nil nil --> constant constant --> constant+ constant --> scalar statement --> statements unconditional --> if scalar --> array array --> container statement --> recursion if --> while expression --> function variable --> assignment simple complex from Robert C. Martin

Christian Fischer TDD Tip #1 Always start with an ordered test list.

Christian Fischer QueryParserTest Query Parser Kata „guitar“ -> [guitar] “red electric guitar“ -> [red, electric, guitar] „red guitar with gigbag“ -> [red,guitar,gigback] „red guitar and gigbag“ -> [red,guitar,gigback] QueryParser + parse(String query): String[] - removeStopwords(String[] words) : String[] „red guitar with 7 gigbag“ -> [red,guitar,gigback] - removeNumbers(String[] words) : String[]

Christian Fischer QueryFilter QueryFilterTest QueryParserTest Query Parser Kata „guitar“ -> [guitar] “red electric guitar“ -> [red, electric, guitar] [red,guitar,with,gigback]-> [red,guitar,gigback] [red,guitar,and,gigback] -> [red,guitar,gigback] QueryParser + parse(query: String): String [] - removeStopwords(words: String[]) : String[] [red,guitar,7,gigback] -> [red,guitar,gigback] - removeNumbers(words: String[]) : String[] + filter(words: String[]): String[] + QueryParser(filter: QueryFilter) -setUpMocks / MockInteractionTest

Christian Fischer QueryFilter QueryFilterTest QueryParserTest Query Parser Kata „guitar“ -> [guitar] “red electric guitar“ -> [red, electric, guitar] [red,guitar,with,gigback]-> [red,guitar,gigback] [red,guitar,and,gigback] -> [red,guitar,gigback] QueryParser + parse(query: String) - removeStopwords(words: String[]) : String[] [red,guitar,7,gigback] -> [red,guitar,gigback] - removeNumbers(words: String[]) : String[] + filter(words: String[]): String[] + QueryParser(filter: QueryParser) -setUpMocks „Guitar“ -> [guitar] - toLowerCase(word: String) : String - toSingular(word: String) : String “guitars“ -> [guitar]

Christian Fischer QueryFilter QueryFilterTest QueryParserTest Query Parser Kata „guitar“ -> [guitar] “red electric guitar“ -> [red, electric, guitar] [red,guitar,with,gigback]-> [red,guitar,gigback] [red,guitar,and,gigback] -> [red,guitar,gigback] QueryParser + parse(query: String) - removeStopwords(words: String[]) : String[] [red,guitar,7,gigback] -> [red,guitar,gigback] - removeNumbers(words: String[]) : String[] + filter(words: String[]): String[] + QueryParser(filter: QueryFilter, normalizer: QueryNormalizer) -setUpMocks / MockInteractionTest QueryNormalizerTest „Guitar“ -> „guitar“ „guitars“ -> „guitar“ QueryNormalizer + normalize(word: String): String - toLowerCase(word: String) : String - toSingular(word: String) : String

Christian Fischer Strong Coupling Parser Module QueryParser QueryFilter QueryNormalizer QueryParserTest Parser Tests QueryFilterTest QueryNormalizerTest public Class package private Class

Christian Fischer Loose Coupling Parser Module QueryParser QueryFilter QueryNormalizer QueryParserTest Parser Tests QueryFilterTest QueryNormalizerTest public Class package private Class

Christian Fischer Leaky Refactoring Refactoring: Split name into two fields.

Christian Fischer TDD Tip #2 Develop your Tests against the Module API.

Christian Fischer In a galaxy (not so) far far away

Christian Fischer Problems • Fixating Design & Framework • Testing implementation, not Behaviour • Speculating about 3rd party behaviour

Christian Fischer The golden Rule ONLY MOCK TYPES THAT YOU OWN from „Growing Object Oriented Design, guided by Tests [Steve Freeman, Nat Pryce]

Christian Fischer Weak Unit Tests Does the Endpoint has the corrrect Path & Method? Does the Deserialization works as expected? Does the Serialization works as expected?

Christian Fischer Two Component Types … • Input/Output • Side Effects • Nonfunctional driven • deterministic • Business Logic • feature driven T echnical L ogical

Christian Fischer Unit Test L ogical § Repeatable § Consistent § In Memory § Fast § Single Concern Unit Test is ... from Roy Osherove: The art of Unit Testing

Christian Fischer Integration Test T echnical § Use system dependent variables § Create object with little Control (e.g. Threads, etc.) § Reach out to external systems § Test several components Integration Test may ... from Roy Osherove: The art of Unit Testing

Christian Fischer Design with CRC Cards Component Reponsibility Collaborators should… • …… • …… • …… calls… • …… • …… • …… from Kent Beck

Christian Fischer TDD Tip #3 Write Adapters for Integration Code and mock these.

Christian Fischer 5 Rules for efficient and effective TDD 1 Develop your Tests against the Module API. 2 Test the Behaviour, not the Implementation. 4 Use Integration Tests for I/O-Components. 3 Don‘t mock external libraries, use Adapters. 5 Make a Test Plan.

Christian Fischer no Multi- Tasking Protection from Overengineering Complexity Partitioning no Fear of Change zero Debug Time Testable Design TDD Benefits TDD

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