Kotlin Clean Code - Speaker Deck

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CONFIDENTIAL & RESTRICTED Mohanraj Karatadipalayam https://medium.com/@kmmraj

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CONFIDENTIAL & RESTRICTED PROBLEM Vs A B Incremental Changes Disruptive Changes

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CONFIDENTIAL & RESTRICTED HOW DO WE REACT? Tools Process Testing Designs

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CONFIDENTIAL & RESTRICTED Receptive to unit testing? Tools support Uses minimal mocking / no mocking at all Soup ? WHAT ABOUT APP ARCHITECTURE?

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CONFIDENTIAL & RESTRICTED UNIT TESTING OF APPS UNIT TESTING OF APPS Trivial ? Code coverage ? How much we test ?

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CONFIDENTIAL & RESTRICTED LET US START WITH UNIT TESTING o Functions are doing everything everywhere o Intertwined o Testing them ? o Mock it ?

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CONFIDENTIAL & RESTRICTED PERFECT UNIT TESTING FRAMEWORK • jUnit • Roboletric • fragment-testing androidx

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CONFIDENTIAL & RESTRICTED “One of the major reasons behind the failure of the unit test automation is an architecture of the app that does not support unit testing.”

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CONFIDENTIAL & RESTRICTED My Journey of finding a unit testable architecture

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CONFIDENTIAL & RESTRICTED Android code has a massive activity or fragment Typical fragment class do the below tasks Data retrieval from data sources Data manipulation and decoration UI Specific activities Life cycle UNIT TESTING IN APPS

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CONFIDENTIAL & RESTRICTED Native Mobile Development Patterns • MVMM • MVP • VIPER – View Interactor Presenter Entity Route • Clean Swift

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CONFIDENTIAL & RESTRICTED CLEAN SWIFT à CLEAN KOTLIN FOR ANDROID

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CONFIDENTIAL & RESTRICTED LET’S SPLIT IT UP 1 Get data from one or more data source à Interactor 2 Modify data in form that can be presented by the fragment à Presenter 3 Present data and listen to user events à Fragment

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CONFIDENTIAL & RESTRICTED Clean Kotlin - Incubation Uni - directional

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CONFIDENTIAL & RESTRICTED How they talk to each other Interfaces

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CONFIDENTIAL & RESTRICTED WHY INTERFACES? MOCK FAKE SPY

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CONFIDENTIAL & RESTRICTED LET’S GET STARTED

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CONFIDENTIAL & RESTRICTED CONFIGURATOR Does the wiring of the dependencies Worried about writing too many boilerplate codes?

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CONFIDENTIAL & RESTRICTED • Smoke test • how do we test the fragment without Interactor? LET’S TEST IT

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CONFIDENTIAL & RESTRICTED MORE TESTING

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CONFIDENTIAL & RESTRICTED • What is the work of Interactor? • data from the data sources like local DB, web service and content provider INTERACTOR

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CONFIDENTIAL & RESTRICTED INTERACTOR CODE

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CONFIDENTIAL & RESTRICTED • If the task is simpler, you can have all the work done by the Interactor itself. • When you foresee that the task can be reused somewhere else in the app, move it to the worker. WHAT IS THE NEED FOR THE WORKER?

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CONFIDENTIAL & RESTRICTED • Call back Hell ? • Use Rx | Kotlin Co routines WORKER

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CONFIDENTIAL & RESTRICTED • We don’t need a real worker, let’s create a spy. • And Spy for presenter INTERACTOR UNIT TESTING

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CONFIDENTIAL & RESTRICTED UNIT TEST IT — PIECE BY PIECE

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CONFIDENTIAL & RESTRICTED What is the work of Presenter? PRESENTER

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CONFIDENTIAL & RESTRICTED • Date of travel is in the YYYY/MM/DD PRESENTER

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CONFIDENTIAL & RESTRICTED PRESENTER

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CONFIDENTIAL & RESTRICTED • As usual -- Mock or Spy? PRESENTER UNIT TESTING

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CONFIDENTIAL & RESTRICTED PRESENTER UNIT TESTING

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CONFIDENTIAL & RESTRICTED ROUTER https://medium.com/@kmmraj

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CONFIDENTIAL & RESTRICTED ROUTER https://medium.com/@kmmraj

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CONFIDENTIAL & RESTRICTED UNIT TESTING ROUTER https://medium.com/@kmmraj

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CONFIDENTIAL & RESTRICTED CONFIGURATOR https://medium.com/@kmmraj

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CONFIDENTIAL & RESTRICTED TOO MUCH BOILERPLATE CODE? https://medium.com/@kmmraj

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CONFIDENTIAL & RESTRICTED References • https://medium.com/@kmmraj/kotlin-clean-code-for-android-series- f3b32307342d • http://bit.ly/KtlnCC4Drd • https://github.com/kmmraj/kt-clean-code4Android-generator • https://github.com/kmmraj/KotlinCleanCode4Android • https://clean-swift.com/ https://medium.com/@kmmraj