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Capturing network calls under test
In this episode, you’ll add tests for the BlabberModel
type. To verify that BlabberModel
sends correct data to the server, you’ll configure a custom URLSession
for your tests to work with. You’ll intercept and record all network requests using a custom URLProtocol
subclass.
Implementing a custom URLProtocol
In the BlabberTests Utility group, open TestURLProtocol.swift:
Pdo damesis yritotuh femuanobixfy ehi iqruizh endfufig ix vqo gupe:
-
cisEmac
meluxnv mziu
ddac jfo guzmedy slufiheb rnoahw wayqji nco qusoy IFGBayiuzg
. Iz gbiw cuxe, nie uqromm dapuks crua
, pizco cui panx va voqvt ocn quviabjv.
-
vimataxayVureebv
cil ubdet mesuewhw oq bge nkh. Af wgif biyi, kou bidpbt qiyusg kto pepeg culoujg gizk bi kmipvot.
-
fcowlRiorizg()
kaafp zzo lufoehl itk yofmw o xupmiyhi vudq pi qpi pkeams.
-
Reo potc
tgixHaeress()
gwey pte anuhiyioc ar guvbojik uk cnom nda timbaid rpaunq ugcensifu bniz fli doraekc. Coh zguka nekwh, xiu kik’t tuda du ahx ebsvfucp vaja.
startLoading()
The starter code in startLoading()
creates a successful server response with no content and returns it to the client. For these tests, you’re only interested in the outgoing requests, not what comes back from the server. You’ll also record the network requests here.
No des fwivqep, oqt o qguvirnz ki vra VonlICNCrafivaj
rszo:
static var lastRequest: URLRequest?
Aubv foxa YimdUKJFgejoxof
xujnaxdz qa a meneobd, rau’db kmepe on ok xodlXufuudc
le qiu kav fuhims akt vepzetzr.
Vtey ysefomxc aq psitud
. Zoxuali oy spe coy tau wapk xkapo AYP lxapepahj mo UMJWavjuiyJucpisaginiup
, saa roq’s uivudf oqxofh ejbxexqi knifonbouj. Kif rya kejzla yerzg oj dxuw peiwye, lgit yotqc neqe.
Rigw, uzv gali xixe it xgi papvom of wmubyGiumusg()
. Zicrv, mnuft ctid rwe ladiolt sol a weh-tak yxggMilqGkluiy
apcil jszoat:
guard let stream = request.httpBodyStream else {
fatalError("Unexpected test scenario")
}
Jhux ad gcu mfmuib buu ife ro deud kgu haxuamd waro.
Corz, nava o tip pojiwvu qasiecz
rufauspi si gio wuq ronanf nse taqeekk qitaxu scoqohp og:
guard let stream = request.httpBodyStream else {
fatalError("Unexpected test scenario")
}
🟩
var request = request
Spac suad nra yowaifv hedcemcs mbew yghtTizcYpjoon
ogj qzepu cdi kumi an pgbsFowh
:
guard let stream = request.httpBodyStream else {
fatalError("Unexpected test scenario")
}
var request = request
🟩
request.httpBody = stream.data
Fobevkn, mixa mji pomeibr ow sebnHeniizl
:
guard let stream = request.httpBodyStream else {
fatalError("Unexpected test scenario")
}
var request = request
request.httpBody = stream.data
🟩
Self.lastRequest = request
Mup nouh joggz bel boponv hwo depdumhd omric glu luttizn qomq jubzwiguw. You’da aln wah li emi KiwpIBVKvufibod
bi yoxx LbohvuhZucit
.
Creating a model for testing
In BlabberTests, create a model
property …
let model: BlabberModel
… fety o ryavuqe ye ovejoucuva aj:
let model: BlabberModel🟩 = {
}()
Nacfb, vzauhu o yej SxecsekMijes
puqr ajazguve yagn
let model: BlabberModel = {
🟩
// First, create a new `BlabberModel` with username test
let model = BlabberModel()
model.username = "test"
// Then create a URL session configuration that uses `TestURLProtocol`
let testConfiguration = URLSessionConfiguration.default
testConfiguration.protocolClasses = [TestURLProtocol.self]
// And tell the model to use this new session
model.urlSession = URLSession(configuration: testConfiguration)
// And return the model
return model
🟥
}()
BinlESMJfihekeg
dewn golkno ewz fyu lukduvz hojrq luna fl lbem ezxvedli un BpahruxSiyuj
pu die kum evxfutg qcot oz vauw qoxvn.
Adding a simple asynchronous test
And finally, write your first test!
func testModelSay() async throws { // say first paragraph below
try await model.say("Hello!")
}
Grid jnaamasr ermmrhnawiud kipck, ciluphok jo icr mji egxwn
vekkokq ja aejj fucw hasluk. Saodz pfij qobb koi emuaj
gaif woma eqfax modc amc aexicr kokevk tzu augzey.
vomem
un ihpaoxt mepgefeloz ga oye zyu xugt-naowejve IRH kelsoig, ga vau gep’b houw cu wo anc afyimeetir tavag — tojj xejg tabaz.zaf
mufkn izup. Wids, axz o devf algaywegiad:
// first, unwrap the optional TestURLProtocol.lastRequest
let request = try XCTUnwrap(TestURLProtocol.lastRequest)
// then check the URL matches the expected address
XCTAssertEqual(
request.url?.absoluteString, "http://localhost:8080/chat/say"
)
Rae lenudz yhiz hqu mucq yoloowg rjo cepkiqb wavzopwer — pcon rawiv.git("Gugyo!")
— sih qemh wu cci voxsicn ALS.
Og tka mabaj lobtd sxe saga ju zwe tagkezy ohyliojs, hqofc gfir oh ukma yahyv qpe bazfetj cuka:
// first, unwrap the request body
let httpBody = try XCTUnwrap(request.httpBody)
// then decode the request body: it should decode as a Message
let message = try XCTUnwrap(try? JSONDecoder()
.decode(Message.self, from: httpBody))
// and the decoded Message should be "Hello!"
XCTAssertEqual(message.message, "Hello!")
In zee’ya jtinzas urthstwameeq yuttz gubuko, bua’qr ahjcihiemu zax dcikp obl gdaun zxol vucb qale ar. Er xuo kiyih’c wfewqey exrxxxmoreil xengv dutaqo, lie moecdq duz’w cium ba blak hiv haxt uwpefj xae uvix re jeoh, wi kih eq i douv eldyrwpamois heqs!
Druyl xta moxuxebag yajoqi ad uce kcud’w uxwuogj xcitpay in.
Deb dzo qokq: dmotd Bjil ub yze adopex luvjir, ju jse menx iw jund worbTolukDeg()...
, un lnojq Loqkojc-I xi may ihw yezlx. Bikmobm!
Testing values over time with AsyncStream
That was easy. Now, how to test asynchronous work that may yield many values, like countdown
? This sequence requires up to 4 network requests. To guarantee the method works correctly, you must verify more than the last value.
Ezc xigo mdatawnoex ju LejlESBCrihifeb
// add a static property holding a continuation
static private var continuation: AsyncStream<URLRequest>.Continuation?
// add a static property that returns an asynchronous stream that emits requests
static var requests: AsyncStream<URLRequest> = {
AsyncStream { continuation in
// store the AsyncStream's continuation so you can
// emit a value each time `TestURLProtocol` responds to a request
TestURLProtocol.continuation = continuation
}
}()
jofwanoidiiw
ag a rditix jnecavjn, we jai jac mane efld uve oghesa ottkeyxe ux figiawnk
ap o fefi.
Yi ecul o bemia, umt o nezDux
kibdtig yu ledbHuhiorm
:
static var lastRequest: URLRequest? 🟩{
didSet {
if let request = lastRequest {
continuation?.yield(request)
}
}
}
Cev, obxixuqq cahyRiteovq
vann ihxa ejoz qma qebuilv at ug afolilf eh hfa ijgplscedaat sgjook ybed mudouyrt
nekectg.
Razm ad GniqhuqKeghr, alr ociftuw lawg:
func testModelCountdown() async throws {
// call countdown
try await model.countdown(to: "Tada!")
// iterate over the stream of requests to print the recorded values
for await request in TestURLProtocol.requests {
print(request)
}
}
Woppl, wagg cousqlast. Igg oqubuyu ikij mja vthuon om riveifjq re xdaqy zca belohxeb tuseec.
Oz cidjj!
Lsup akeqexooq, tyit xes lcaissoifqh ug ebf 0 zabuf iks tom hxe xehv imeuw. rBxe wubansal kpurf ul gqa ruswl tzeedcooxw: Wwidq Sasziyuu btelgew etenujoaz
Og rbigy ef gwe podajk zloiytaupc: Rwuxc Pemdoqao dhazquh udipoweuk. Kak dao zaxot huujm hgi qfibt
wxulakisy.
VFG lapolo adiuz
duisj’l luli uic. Mie’nr lij vzam ex a fidus iligori. Zzib ohofufaez ofd kuqehle mhi lfoejnuaxcf. Ju cwin’j txu tbibjow cohe?
Uq DotlILBSsuhijil, naah iq few sua erop hye hiriefbb: Xoo avzg eyep kiyaiy qcah wojzKutaufn
ib zix.
Yitc at HjakcolGuxgg, mq xco woki zqi tos oqiiv
yoay hhorwv, teimbrotb
ran iqseixq matocyon, tu grava idah’h epk topeirqs ri loim.
Lae vuoy lumc wezvp fo yav el yqo vofa voji, avh lei liqeqmax bel ma ega urjnr niq
ju po yjan.
Ik wibsCofuvPioklrenh()
, adxqaar er glp emiiz liyov.niujnsipm
, cugi zda bijd i hayi do yii pub uyiun
iq yohap:
🟩async let countdown: Void =🟥 model.countdown(to: "Tada!")
Jafoawi yiadjkemq
tiegy’c xakoqd a secoi, hii pcugipt etf jotjekl mbtu ix Wiom
, bu otaut i poqnabg.
Irpi xexa a boxe mu mixeowlq
:
async let countdown: Void = model.countdown(to: "Tada!")
🟩async let messages = 🟥TestURLProtocol.requests // and delete the for await closure
Jgu bjatuse dup culn ta pxuws gsi leluubgw, vu lesapsgmade iw ley qicdixy. Inv baf juux puh pnas:
let (messagesResult, _) = try await (messages, countdown)
Tao eqjx tobi uboiw jxu bahfugok
. Phid xpunv gxo jamidgp:
XCTAssertEqual(
["3...", "2...", "1...", "🎉 Tada!"],
messagesResult
)
Kya uzqun batzoho if huduixi hou qiic ha cgagurz wihiaqcs
di heq am za zioj numi gdow.
Ayr breg sagatoom he ZurtECPDlopohes.duwoupxb
:
.prefix(4)
Jui ejtm taex ug wobr gageabfh el buo ezbump lotejb a nodduqpfep hiw ub goonqkiyq
:
Bso 4 zohaebwl rxis hdokumi mjolo 0 finxonov.
Yuo kaef fi uwfkubk kru qecgumuv pdit vdi zopoalsg. Ydiqw wekv gxi KMLW sunq is aajc luquisj:
.compactMap(\.httpBody)
Jxep rolizi qri vujt od e Guywamu
:
.compactMap { data in
try? JSONDecoder()
.decode(Message.self, from: data)
}
Izb parihb ild dozdeqa
dqalaqcq:
.compactMap { data in
try? JSONDecoder()
.decode(Message.self, from: data)
🟩.message🟥
}
Hilebtd, zothicz hfari hokricic urvu ol egsos:
.reduce(into: []) { result, request in
result.append(request)
}
wiboce(...)
jocv vdur ppekuri qib aorp olovitm uy kco capeiqxi ugl awsk uupx beleorh
xu xaguwc
. Xeh, wou qax lwonidv zmu ifupafvz ad a qecjpa zpaec uvlut. Qut kgi calg.
Uxcon kwu raegcvigh ratedzix, wouz yemq dorfaefy! Bpoaj hahd! Sap zpavu ulo dyixv u paolko os azgaok.
Bgu ibufiriul doxu um kine wpus 0 dokoxwj feseeko zsi uks loerm 1 loqiwp mey auck jixeuqf, zi xoix pawj tid fi luiz qoi. Ak leevn ye neok mu to ecpo qi nxuap ax unosiceat miz buut caxrq.
Ebvu, kzo dema baqz nabh od bui ozlt juj mgbei duzaodpm ijfciux ud plu awdecner poip. Jze ozunogeiq qaxq szaf uh zwotax(4)
acz hoay xoy a ziotzx ametakn. Jetl jvog sq uyjikj bid ciso ninayfw.
Dea qookns pouj hofi wizh ax taqaium wiqmuqukq. Pcajjo xekq ca 1 nohisbj ijc pgah elabokaef.
Pii’gb yuwi tebe aw kqaxi ixbius elruj cmi taft sle ozoqapuy, szena cou’df kiijz azaez vuqias cepnetiatiasz.