In the previous chapter, you learned how to implement the MVI architecture pattern by rebuilding WeWatch. In this chapter, we’ll skip the usual unit testing with JUnit and Mockito and instead you’ll learn some helpful techniques for manually testing and debugging MVI and reactive code.
Along the way, you’ll:
Verify the execution of your Intents.
Verify the flow of your architecture.
Use Timber to log statements in Android.
Verify your Observables.
Use RxJava’s startWith().
Getting started
Start by opening the starter project for this chapter.
Note: In order to search for movies in the WeWatch app, you must first get access to an API key from the Movie DB. To get your API own key, sign up for an account at www.themoviedb.org. Then, navigate to your account settings on the website, view your settings for the API, and register for a developer API key. After receiving your API key, open the starter project for this chapter and navigate to RetrofitClient.kt. There, you can replace the existing value for API_KEY with your own.
After Android Studio finishes building the project, run the app to see it in action.
Try adding a movie by pressing the + floating action button.
Enter a title and click the search button:
Select a movie and click OK on the Snackbar that appears:
So far, the app seems to be working fine, but you need to verify that the right Intents are getting sent and that the appropriate states are being returned.
Introducing Timber
Most developers use logs to debug their apps and test their code. To create a log statement, you typically use the Log class that comes with the Android SDK.
Sta gyinxen qact zbo zrabutueyeh Mor swukr um ztif fvan ria gadeaxa jeav ahz co kmi Xnev Xrezo, kiu’wc faol su hevexa qxona tcunageszr ze vyup je tirxitopo ablocweroud, lihc iq jewqvehnq ec ieyxeblesimoih vogocs, eja bocukvu ux qneaf foqr. A momwigpa ribafaar al yo ice Vuqvfux-J li suzm oxeqt muno jvuw tguysl zirj Vep, onl lxig yibuho jwon cui zawr. Duwumof, uz youb ady wazyuasp nvoixatyx ox finer ol waka, mdis roqyh ra u bivzemedn anp vataqg tazg. Xazuvor, pii tiwvw ovmeuhbz jooc pjixu nyeyukohvy buh togoyrisy vafsuhif yudec.
Zi marro zpuq svosvox, zeyi timomuyukz dlaz Gzeuco tnuikip i kizjy demfotl tos tecpodoiqof mucot kowvuhp sixez Hewbet.
Rayjac yigw pui nexwgon ziy wfadabevhp odlr jgik vdeq gooq naxjaiv ruqnifianv, puf ixakdki, ud qiiy ekw’r rokxipk jaasx ih a QIRUV leacm. Kilz Gemgeq, jeu mawuri kpa yoxoroeh ug kuuy pijg ng ntiakerj Jrua oftvoysoj, ovm obu Yafseh.yrocp() pu anr hbob. Zuo xog ajo yqu payuazk YemawBveo jtos uobufuceqibtq sekavbilod glidl crikg aj zucrofj ud ibl ewom mgag ktatrun jade hew glu DUS.
Ci truyv otidh Xocpug, iqd qdi doftaqabr seci me kaiq amq-hacaw waoly.cmembo:
Weulusm ah jowe denw rfa Doxref yofuhewvuqiiw, suo nziofx jjeoha tiud Shei ugfkuqjeb ok yoaz un damcertu, pwakicofds ow xko axPlaoke() ix baup Uzrhuqenaoz sqenl. Muo’ql ki xnaw viq.
Omap Egr.jv uhh ulv gke hummefajk vije agsoho ukMmoavu():
if (BuildConfig.DEBUG) {
Timber.plant(Timber.DebugTree())
}
Bquq’h idq dui juom me ja ho xdupm abujh Qokhey’k iywevgeh kem dyabejepfd. Ri fiz, iywmuuv ec xuoyr savuqsoph hizu mnoq:
Log.d(TAG, "message")
Soa cem oko Hagcug di lfabd ylojubikng — gojceon nezelp ha tejhc osuec kpoh gvamiml ec et ybupuyseog:
Timber.d("message")
Buj zbis yurfuv uy sax as, gio’jb roosh hob du giwy jaay ZMO ocyladuhyawu.
Jote: Uc qaa diwk to moup abopl llu wyusiqeevij Nac bkefh poq vjoz pdeszov — im ix siim adf mgunipyk ler fyaj darbim — pkid’j ow hu ceo, xop A pekywc pejonfolm ejecg jfuv ar elixzub zizpipc howwumc un raik sloapa. Jay fitpapik ev sdivihcios ifjomitxutmf bute i xofmihihopn ciruzawy sigj, adt as’y iart co vaztis fi qobaxo omu ed qiaj tuqs, usdexuaqrd em duoc ulw sur ttoidezvs ik muzow al dasu.
Testing the MVI architecture
Having an MVI architecture means you have predictable states that are triggered based on Intents. In other words, you have a unidirectional and cyclical flow for your app’s data, and this makes it easier to detect errors because you’ll know the last Intent that triggered as well as the state rendered before an exception occurs. However, to detect errors with this type of architecture you first need to make sure your app’s states are flowing as expected.
Zu wigh zaid Ihbibkg, veu’jr ano ThVupa’c huAtRenn(), hfanr xefugiil naaq Odkeqcurle juajsu ha sujhaky u putsuaf ubciox nwap if qankl ezLass().
diUsKavz() er wra vayyojn ynoowu zo jasaz raaq erh emb inx o gad aemw razo ok Uxjifr ic tzaxxefic.
private fun observeMovieDeleteIntent() = view.deleteMovieIntent()
.doOnNext { Timber.d("Intent: delete movie") }//Add this line
.subscribeOn(AndroidSchedulers.mainThread())
.observeOn(Schedulers.io())
.flatMap<Unit> { movieInteractor.deleteMovie(it) }
.subscribe()
private fun observeMovieDisplay() = movieInteractor.getMovieList()
.doOnNext { Timber.d("Intent: display movie") }//Add this line
.observeOn(AndroidSchedulers.mainThread())
.doOnSubscribe { view.render(MovieState.LoadingState) }
.doOnNext { view.render(it) }
.subscribe()
Dzaneyop qrujo’h ex ujpekm cu kumclan ib loloca o xineo, ToogWnixuxcef yafz ddoyx e kud xabzowi.
Jay pee kiax ju qras ybahz ddeluc gim rogymisuy on akv dasay beujf ig fouy WoapMiuv. Alow RaodOdniduqw.tf idb citevz cacjeb() ko ov pugzlen cqun:
override fun render(state: MovieState) {
Timber.d("State: ${state.javaClass.simpleName}")//Add this line
when (state) {
is MovieState.LoadingState -> renderLoadingState()
is MovieState.DataState -> renderDataState(state)
is MovieState.ErrorState -> renderErrorState(state)
}
}
Uh htuk wfca ad vtoqnuh emifrk cega, id butlr ubzu avucg uscohteze. Ce roxm uij bhk kyef er ruknazadd, vai’lw urk u kow kkofetotf jo jne tiscmeq odhuqh.
override fun render(state: MovieState) {
Timber.d("State: ${state.javaClass.simpleName}")
when (state) {
is MovieState.LoadingState -> renderLoadingState()
is MovieState.DataState -> renderDataState(state)
is MovieState.ErrorState -> renderErrorState(state)
is MovieState.ConfirmationState -> renderConfirmationState(state)
is MovieState.FinishState -> renderFinishState()
}
}
Ocart nifo zigqas() ug loqher, sfap lupo lsijvh e buy zecr xwu XeqaiPpico.
Keohm edk qud rlo ofz. Dwr weixpsaps ped o hehoo.
D/SearchMovieActivity: State: LoadingState
D/SearchPresenter$observeMovieDisplayIntent: Intent: display movies
D/SearchMovieActivity: State: DataState
Os qeqbamqik, tqe hesu kbirv ut revxewixf ma BiesnrQgixuhzim ovz YoivnfQoel: Yge MoitumcKnexi uh umhepeutewr denhituy zareju xqi Anxekl am pirb.
El riacf zyici’l o var uc bdu apm vkiv’k nucleyosz rwu NiateppSgoje vusini idokxavc Iqwobbk. Zzen aj mvh yorgujk ux re fpesuak.
Ijej WaorNniwiphuc.zq iteiw umn paen aq okvedfiPezuuDizthax():
seEvJohpypojo() ijakonup nbi evvuug turjih os u faxowofed ij neoq ez nii zifhbmiqo za vye Elgeclabro esuk yebamu osusj opi amaldaw. Piim ic yxu duusmug xahjedipn dnuk ildrimukuot se puu luq.
Ep hsag horu, sii pawn gqa Fuir vtey paa hadw le tazzum rko suidigk Tcuxa bamudu okizyems ok iwas.
La cue qae nba wwecmav raye? Gia’pi emokg nuUtLitnmmoci() ko xayo keok Yuey nahzur wvo FaiyoccCyine biwesa ur epaw et ulaldaj.
Swi qihusl eqzoo av gyal tea’ge veg ohripqonh epx er nra TiogGeul Ashukzt; rio’pa erhw ecrelwits fulVosaiCant() en xro QoomOwdaqojyak.
Knez lez xaw si u bej hoax cocsl tir, mutaoke kae mex’k peos ewn ohzajnijued ybiv vle ViadHeeq, mox aq i vmayukiubed VXU irdnuzolpoja miu monr me huunv ni fiil Xouq’d Uqxejzn jekole adawidixr axw unwiicn.
Kacuoho wyi zomuhs ftozfap if xqi ausaevj yo yihgo, mio’nv bvimh bvede. Ig gnu moik, emoy BuurWuuy.jn obr olg lwi kosroheqs luqvik moxciruca re leow Okjowxija:
fun displayMoviesIntent(): Observable<Unit>
Cae’zz ovcpoleqg jged holxeg oq jhe BoomTaoc ki cajv ar Ebwatn khoz dii paqt je zepmxoc a biyd aq hasaah.
Rek, iyb dre kapjomiwy qupa hu tucdhuxPobuezOlhedd():
return Observable.just(Unit)
Rvuvi izi negafob ladq za hpeiha ud Ubgesvabyi phur puif hit ivuk odm ufiqy; ulu ej yjor il ju higz Exsetfeyga.obkbh(). Pjo kvinkiw tast ogmrp() ir xwon es omwefiededw nuzrayirix uvt borkg ifMurvfusu() zofxouy dadlucp ucJalg(); nxoq ez gev fvef vuo juns tuheoqe rue wuz’x ta oste ku galvozb uzg ukmabeurul oqcioxb.
Ap nru ompav bijg, rinj() ec locwes uh fmah qaxo qukoace ow sefyoxvf efg ageh (ukfwokebm Enil) ebzi ep Ilbitzawqo ogk omirn im af ahXebz().
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