Keeping Your Users Happy With Testable Apps

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Greg Shackles OLO @gshackles [email protected] github.com/gshackles Keeping Your Users Happy With Testable Apps

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TDD

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TDD KISS SOLID BDD DRY SOC YAGNI DDD SRP OCP LSP ISP DIP XP IOC CQS

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Why Test?

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Stability

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Stability • Obvious, but important

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Stability • Obvious, but important • Refactor and iterate with a safety net

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Stability • Obvious, but important • Refactor and iterate with a safety net • Compilation is only the first unit test

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Stability • Obvious, but important • Refactor and iterate with a safety net • Compilation is only the first unit test • Verify cross-platform compatibility

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“I don’t have time to write tests!”

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“I don’t have time to NOT write tests!”

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Once It’s Out, It’s Out

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Once It’s Out, It’s Out • This isn’t the web

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Once It’s Out, It’s Out • This isn’t the web • Diﬀicult and expensive to fix

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Once It’s Out, It’s Out • This isn’t the web • Diﬀicult and expensive to fix • Quality bar has been raised

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Once It’s Out, It’s Out • This isn’t the web • Diﬀicult and expensive to fix • Quality bar has been raised • Bad reviews stick with you

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The Happy Path

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• Improves design The Happy Path

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• Improves design • More shared code (not just mobile apps) The Happy Path

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• Improves design • More shared code (not just mobile apps) • Optimize independently of a platform The Happy Path

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• Improves design • More shared code (not just mobile apps) • Optimize independently of a platform • IterationSpeed++ The Happy Path

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• Improves design • More shared code (not just mobile apps) • Optimize independently of a platform • IterationSpeed++ • FACT: Green tests are good for the soul The Happy Path

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What To Test?

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What to Test?

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What to Test? • 100% code coverage != the goal

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What to Test? • 100% code coverage != the goal • Test parts that provide value

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What to Test? • 100% code coverage != the goal • Test parts that provide value • Testing platform code can be diﬀicult

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What to Test? • 100% code coverage != the goal • Test parts that provide value • Testing platform code can be diﬀicult • Start small

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! ! Unit Tests

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! ! ! ! Unit Tests Integra-on Tests

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! ! ! ! ! ! Unit Tests Integra-on Tests UI / UX Tests

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! ! ! ! ! ! Unit Tests Integra-on Tests UI / UX Tests Mixed Automated

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Unit / Integration Tests

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Unit / Integration Tests • Automated

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Unit / Integration Tests • Automated • Low friction

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Unit / Integration Tests • Automated • Low friction • Leverage tooling

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Unit / Integration Tests • Automated • Low friction • Leverage tooling • NUnit (Lite)

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Unit / Integration Tests • Automated • Low friction • Leverage tooling • NUnit (Lite) • Run on all platforms

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Unit / Integration Tests • Automated • Low friction • Leverage tooling • NUnit (Lite) • Run on all platforms • Simulator vs Device

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Mocking

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Mocking • Limited options

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Mocking • Limited options • Manual mocking

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Mocking • Limited options • Manual mocking • Code generation, T4 github.com/gshackles/Muntz

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01 02 03 04 05 06 07 08 09 10 11 12 13 14 Mocking interface IService { ! string Foo(string bar); } ! class MockService : IService { ! public Func FooBody { get; set; } ! ! ! public Foo(string bar) ! { ! ! return FooBody(); ! } }

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Manual Testing

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Manual Testing • User feedback is critical

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Manual Testing • User feedback is critical • UX testing

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Manual Testing • User feedback is critical • UX testing • Exploratory testing

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Manual Testing • User feedback is critical • UX testing • Exploratory testing • TestFlight testflightapp.com

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MVVM

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MVVM • MvvmCross

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MVVM • MvvmCross • Shared, testable view models

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MVVM • MvvmCross • Shared, testable view models • Improved IoC support

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MVVM • MvvmCross • Shared, testable view models • Improved IoC support • Databinding keeps views thin