A presentation at QCon London 2015 in in London, UK by Savvas Dalkitsis
How to build rock-solid apps &"keep"100m+"users"happy" Iordanis)Giannakakis)) iordanis_g " Savvas ) Dalkitsis )) @ geeky_android "
qconlondon "
How Shazam works
Some numbers
Happy users Even developers?
Android testing
Faster release cycles
Better code
Cheaper http://testdroid.com/testdroid/5851
Easy
A user walks into a bar
Doing it the test driven way "" "" Write"UI" test" Implement" Refactor " Write"unit"test" BDD" TDD"
Test first • Generally easier • Eliminates external dependencies • Easily repeatable
The Acceptance Tests cycle "" "" Write"UI" test" Implement" Refactor " Write"unit"test" BDD" TDD"
Acceptance criteria • Given: arrange • When: act • Then: assert
Example Given a user is near a music venue And the server always returns a known result
When the user Shazams
Then the user can check-in their discovery
gwen
!given(user). isNear ( lexington ());! !given(server).returns( lustForLife ());! !! !when(user). shazams ();! ! !then(user). canCheckIn ( lustForLife (),! lexington ());! http://github.com/shazam/gwen
Other libraries for Acceptance Tests • Instrumentation • JUnit 3 • Espresso & Robotium
• Fork • HamMock Server
The Unit tests cycle "" "" Write" UI"test" Implement" Refactor " Write"unit" test" BDD" TDD"
What we don’t test Activities & Fragments http://github.com/xxv/android-lifecycle
What we don’t test
What we do test
• Presentation logic • Business logic • That’s it
The MVP pattern
Presenter Model View
The MVP pattern
Presenter Model View Android
The MVP pattern
• Makes presentation logic testable • No need to test “dummy” view • Avoid Android dependencies
Dependency Injection, Yourself
• Breaks hardcoded dependencies • Behaviour
vs Implementation • Implementations for test & runtime
Feature X Hardcoded dependencies
Client Feature X
Dependency Injection
Client Feature X Interface Injector"
Model !public ! interface ! VenueRetriever !{! !!!! void ! findClosestVenue ( VenueFoundCallback ! callback );! !}! ! !public ! class ! NetworkVenueRetriever ! implements! VenueRetriever !{ ! !!!!public ! void ! findClosestVenue ( VenueFoundCallback ! callback )!{! !!!!!!!//!Some!slow!networking! !!!!}! !}! ! !public ! class ! LocalVenueRetriever ! implements! VenueRetriever !{ ! !!!!public ! void ! findClosestVenue ( VenueFoundCallback ! callback )!{! !!!!!!!//!DB!lookJup!/!caching!layer,!perhaps?! !!!!}! !} "
new ! ResultPresenter ( this ,! venueRetriever ,!result);! !!}! ! !! public ! void ! onStart ()!{! !!!! resultPresenter .startPresenting ();! !!}! } "
Presenter !public ! class ! ResultPresenter !{! ! !!!! public ! ResultPresenter ( ResultView ! resultView ,! VenueRetriever !! !!!!!!!!!! venueRetriever ,!Result!result)!{! !!!!!!! this . resultView !=! resultView ;! !!!!!!! this . venueRetriever !=! venueRetriever ;! !!!!!!! this . result !=!result;! !!!!}! ! !!!! public ! void ! startPresenting ()!{! !!!!!!! resultView .showResult ( result );! !!!!!!! venueRetriever .findClosestVenue ( new ! VenueFoundCallback ()!{! !!!!!!!!!! public ! void ! venueFound (Venue!venue)!{! !!!!!!!!!!!!! resultView .showCheckInPrompt (venue);! !!!!!!!!!!}! !!!!!!!});! !!!!}! !} "
View !public ! interface ! ResultView !{! ! !!!! void ! showResult (Result!track);! ! !!!! void ! showCheckInPrompt (Venue!venue);! !}!
Activity !public ! class ! ResultActivity ! extends !Activity! implements ! ResultView !{! ! !!!! public ! void ! showResult (Result!result)!{! !!!!!!!// TODO !show!the!result!screen!&!bind!result!data! !!!!}! ! !!!! public ! void ! showCheckInPrompt (Venue!venue)!{! !!!!!!!// TODO !bind!the!venue!with!checkJin!prompt!view! !!!!}! !} "
Other Unit Test technologies • JUnit 4 • Robolectric
java.lang.RuntimeException : Stub!
• Hamcrest
• JMock
Test execution
Continuous Integration
Speed (Hint: slow)
Usual execution Test"Suite"
Spoon http://github.com/square/spoon
Fork http://github.com/shazam/fork
Test"Suite"
Example
Fork http://github.com/shazam/fork
Fork http://github.com/shazam/fork
• Pooled execution • Infinitely scalable • Current setup 1 test / 2 seconds
Flakiness monitor
ADB Remote http://github.com/sleekweasel/CgiAdbRemote
If all else fails
If all else fails
If all else fails
Summary • Testing is easier than you may think • Practice, practice, practice • Toolset is limited but getting better • Ship it!
Questions?
Shazam is a very popular audio recognition app. It is installed on 100M+ Android devices and it’s growing rapidly. In this talk, we would like to address how we have made our releases schedule faster, more predictable and with more features by using BDD and automation testing. We will demonstrate how that can be done without slowing down or hindering the development process and why our developers actually find writing tests is fun. Finally, we will look at how our testing strategy has translated to our testing framework and hardware infrastructure.
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