CYA: Cover Your App

Jorge D. Ortiz Fuentes @jdortiz

A Canonical Examples Production

#AdvArchMobile

Agenda★Motivation

★ Facts

★What’s missing?

★Architecture

★ Live Coding

★Recap

Motivation

But my code is always awesome!

#AdvArchMobile

Selfish Unit Tests★No more discussions

★No more explanations to the team

★No more questions

★No more bugs introduced by them

★No more missed deadlines

★No more late hours

#AdvArchMobile

Selfish Unit Tests★Prove (to others) instead of (your) intuition

★No more explanations to the team

★No more questions

★No more bugs introduced by them

★No more missed deadlines

★No more late hours

#AdvArchMobile

Selfish Unit Tests★Prove (to others) instead of (your) intuition

★Define contract and assumptions

★No more questions

★No more bugs introduced by them

★No more missed deadlines

★No more late hours

#AdvArchMobile

Selfish Unit Tests★Prove (to others) instead of (your) intuition

★Define contract and assumptions

★Document the code

★No more bugs introduced by them

★No more missed deadlines

★No more late hours

#AdvArchMobile

Selfish Unit Tests★Prove (to others) instead of (your) intuition

★Define contract and assumptions

★Document the code

★Easier refactoring or change

★No more missed deadlines

★No more late hours

#AdvArchMobile

Selfish Unit Tests★Prove (to others) instead of (your) intuition

★Define contract and assumptions

★Document the code

★Easier refactoring or change

★Better estimations for tests than debug

★No more late hours

#AdvArchMobile

Selfish Unit Tests★Prove (to others) instead of (your) intuition

★Define contract and assumptions

★Document the code

★Easier refactoring or change

★Better estimations for tests than debug

★Reusable code = code + tests

Prove correctness of different aspects of the public interface

Test the parts that you aren’t

developing now

Facts

Coverage =

Measurement

We want: “Code is proven

correct in all cases”

We get: “Lines used by the

tests”

Demo: Demystifying

Coverage

#AdvArchMobile

What you have seen★ Full CRUD

★100% Kotlin (everything but generated code)

★Mockito + Mockito-Kotlin

★Good architecture

★TDD

What is Missing?

#AdvArchMobile

Not Covered

★Dagger factories

★Platform: implementation details (activities, adapters, application subclass, DI)

Let’s do better

Architecture

MVP

ViewPresenterModel

display commands

events

fetch/changedata

Test View Methods

ViewPresenterModel

display commands

events

fetch/changedata

Test Events To Presenter

ViewPresenterModel

display commands

events

fetch/changedata

Presenter

#AdvArchMobile

How to Mock the Presenter

★App uses Dagger 2 for DI

★Dagger 2 is NOT meant for Unit Testing

★Activities use Service Locator for DI

★Service Locator abstraction is implemented by Application subclass

★Unit tests use another Application subclass

And if I am an MVVM Person?

Live Coding

Let’s write this together

#AdvArchMobile

Recap

★Unit Tests are good for you (and for others)

★Code coverage is not the best metric

★Good coverage is better

★A good architecture will help to cover the different aspects of your

Thank You!

@jdortiz #AdvArchMobile