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ɹɹɹɹ
Server-Side Kotlin By
UPSIDERɹਗ਼ਫݦ
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SELF INTRODUCTION
• ਗ਼ਫݦ(@kaonash_)
• Lead Software Engineer @ UPSIDER
• Ҡॅ͍ͨ͠ܥΤϯδχΞʢ2022ɺʹҠॅ༧ఆʣ
• Love: ୌ / Kitkat / Kotlin
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SELF INTRODUCTION
UZABASEɿاۀɾۀքੳϓϥοτϑΥʔϜͷ։ൃɻServer-side Javaɻ
↓
NewsPicksʢࣾస੶ʣɿܦࡁχϡʔεΞϓϦͷ։ൃɻServer-sideJavaɺAndroidΞϓϦ։ൃ
ͰKotlinॳମݧɻ
↓
Bizreachɿ৽نࣄۀͱͯ͠ैۀһσʔλϕʔεαʔϏεͷ։ൃɻServer-side Kotlin(Spring Boot)
↓
UPSIDERɿۀҰͷελʔτΞοϓʹͯB to BͷFinTechϓϩμΫτΛ։ൃɻServer-side
Kotlin(Ktor)
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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ࠓ͞ͳ͍͜ͱ
• Ktorͷৄ͍͠Έ
• ຊ൪ӡ༻ͯ͠Έͨײʢ·ͩϦϦʔεલͳͷͰɾɾɾʣ
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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Server-Side Kotlinͬͯ͑Δͷʁ
ɾJavaΛ࠾༻ͨ͠έʔεͱൺͯશવҧײͳ͍
ɹɹɹͱ͍͏͔ਖ਼ɺҰKotlinʹ׳ΕͪΌ͏ͱ͏JavaͰॻ͖ͨ͘ͳ͘ͳΔ
ɾܕਪ֦ுؔͳͲͷ͓͔͛ͰඇৗʹεοΩϦ͔͚Δ
ɾnull-safety࠷ߴ
ɾJavaͷϥΠϒϥϦ͕͑ΔͨΊɺΤίγεςϜʹ͍ͭͯ৺ෆཁ
ɾͨͩ͠ɺJavaϥΠϒϥϦར༻࣌ʹམͱ͕݀͠ɾɾɾ
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JavaϥΠϒϥϦར༻࣌ͷҙ
ɾJavaͷϝιουΛݺͼग़͢ͱɺΓT!ܕ
(=T͘͠T?)ʹͳΔ
ɾϥΠϒϥϦଆͰରԠͯ͠ͳ͍ͱnull-safetyͷੈք͕յΕΔ
val message = "test"
val encrypted = StringEncrypter.encrypt(message) // StringEncrypter͕JavaϥΠϒϥϦͩͱ
println(encrypted.length) // ͜͜Ͱ͵ΔΆʹͳΔ͔
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ʮ͔ͤͬ͘Kotlinʹͨ͠ͷʹɾɾɾʯ
ײਖ਼ͪΐͬͱ͋Δ
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KotlinϥΠϒϥϦͳΒ҆৺ʂ
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ͰServer-sideͰ͑ΔΑ͏ͳ
KotlinͷϥΠϒϥϦͳΜͯɾɾɾ
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ࠓΊͬͪΌ૿͑ͯ·͢ʂ
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• Language : Kotlin
• WebϑϨʔϜϫʔΫ : Ktor server
• O/R Mapper : Exposed
• DI : Koin
• Http client : Ktor client
• JSON Parser : Jackson
• Testing : JUnit5 / AssertJ / MockK
ฐࣾͷٕज़ελοΫ
Server
΄΅Pure Kotlin!
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Server-side KotlinʮͰ͖Δʁʯ͔Β
ʮԿΛબ͍͍ʁʯʮͲ͏ͬͨΒ͍͍ʁʯ
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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WHAT IS
• JetBrains͕։ൃͨܰ͠ྔɾඇಉظWebϑϨʔϜϫʔΫ
• ಡΈํʮ͚͍ͨʔʯʢ࠷ॳʮͨ͜ʔʯͩͱࢥͬͯͨʣ
• Pure Kotlin
• PluggableʹඞཁͳػೳͷΈΛՃ͍͚ͯ͠Δ
• 201811݄ʹ1.0͕ϦϦʔεʂʢݱࡏͷ࠷৽1.2.3ʣ
• Server͚ͩ͡Όͳͯ͘Client͋Δ
https://ktor.io/clients/index.html
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Spring Bootͱͷ˒ͷࠩ
·ͩ·ͩ͜Ε͔Β͚ͩͲɺ͍ͩͿ͕ू·͖ͬͯͯΔ
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ͳͥKtorΛબΜͩͷ͔ʁ
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ٕज़બఆΛͨ͠λΠϛϯάɿ20189݄
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ީิ
• SpringBoot
• Jooby
• Ktor
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SpringBoot
• ͍ΘͣͱΕͨJavaքͷσϑΝΫτελϯμʔυɻServer-side KotlinͰ࠾༻ࣄྫ͕ଟ͘ଘࡏɻ
• KotlinରԠ
• લ৬ʢ࣌μϒϧϫʔΫͩͬͨͷͰݱ৬ʣSpringBootͰServer-Side KotlinͬͯͨͷͰܦݧ͋
Δ
• શ෦ೖΓͰศརͳͷ͕ͩͦͷىಈ͕࣌ؒ͘ɺͦͷؒʹTwitterͱ͔Twitterͱ͔Twitterͱ͔Λݟͨ
Γͯ͠͠·͏
• Ξϊςʔγϣϯࠈ͕͋·Γ͖ʹͳΕͳ͍ɻɻɻʢݸਓͷײͰ͢ʣ
• ΫϦʔϯΞʔΩςΫνϟΛݕ౼͍ͯͨͨ͠Ίɺશମ͕ΨοπϦSpringʹґଘ͢Δͷ͕ͪΐͬͱ
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࣮ࡍͷΞʔΩςΫνϟ
ΫϦʔϯΞʔΩςΫνϟͷߟ͑ͰWebϑϨʔϜϫʔΫʮৄࡉʯͰ͋ΓϏδωεϩ
δοΫ͔ΒΓ͖͢ͷɻ
ͰSpringBootͩͱDIΒ@transactionalΒͰશମ͕ΨοπϦSpringʹґଘͯ͠͠·͏ɻ
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Jooby
• ܰྔߴɺPluggableͳJavaϚΠΫϩϑϨʔϜϫʔΫɻ
ࢥ͕Ktorͱ͔ͳΓ͍ۙɻ
• KotlinରԠ
• ଞࣾͷ࠾༻ࣄྫ͋Δ
• ࠷ॳୈҰީิͩͬͨ
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Ktor
• ٕज़બఆ࣌ͷόʔδϣϯ0.9.5
• JetBrainsͱ͍͏͜ͱͰɺࠓޙϝϯς͞ΕΔͩΖ͏ͱ͍͏҆৺ײ
• GithubͷIssuesΛνΣοΫͯ͠Έ͕ͨɺServerଆͰ͋·Γେ͖ͳͬͯͳ͞
ͦ͏
• ʮ0.9ͷ࣍1.0͡ΌͶʁʯˠ݁Ռతʹͨͬͯͨ
• Jooby͍͍͕ɺͲ͏ͤͳΒPure KotlinͷϑϨʔϜϫʔΫΛͬͯΈ͍ͨ
• ʮૣΊʹ࠾༻͢Εɺٕज़తʹΛूΊͯ࠾༻ͱ͔Ͱ༗རͦ͏ʯͱ͍͏ଧࢉ
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݁
ʮͳΜ͔KtorͬͯΈ͍ͨʯ
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࣮ࡍͬͯΈͯͷײ
• ىಈૣ͍ͷ࠷&ߴʢ.ktϑΝΠϧ͕300ݸ͘Β͍ͷঢ়ଶͰϏϧ
υऴΘ͔ͬͯΒ1.5ඵ͘Β͍Ͱىಈྃʣ
• ඞཁͳͷҰ௨Γἧ͍ͬͯΔ
• ֦ுؔɾߴ֊͕ؔ;ΜͩΜʹΘΕ͍ͯΔͷͰɺ׳Ε
ͯͳ͍ਓ࠷ॳͪΐͬͱށ͏͔ʁ
• શମͱͯ͠ͱͯຬ
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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ͳʹͱ͋ΕHello World
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Hello World!
Ktor serverͷىಈํ๏͍͔ͭ͋͘Δ͕ɺҰ൪؆୯ͳํ๏
fun main() {
embeddedServer(Netty, 8080) {
install(Routing) {
get("/") {
call.respondText("Hello World!")
}
}
}.start()
}
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Hello World!
fun main() {
embeddedServer(Netty, 8080) {
install(Routing) {
get("/") {
call.respondText("Hello World!")
}
}
}.start()
}
NettyΛར༻ͯ͠ΞϓϦέʔγϣϯΛ࡞
port൪߸8080
Get methodͰpath"/"͕ݺͼग़͞ΕͨΒ
responseͱͯ͠"Hello World!"ͱ͍͏จࣈྻΛฦ٫͢Δ
͜ͷblockͰroutingΛఆٛ
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ΑΓॊೈͳىಈํ๏
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EngineMain
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EngineMain
• EngineMainKtor͕༻ҙͨ͠Ϋϥε
• ར༻͢ΔEngineʹΑͬͯ4छྨ༻ҙ͞Ε͍ͯΔ
• io.ktor.server.cio.EngineMain
• io.ktor.server.tomcat.EngineMain
• io.ktor.server.jetty.EngineMain
• io.ktor.server.netty.EngineMain
•mainؔΛ͍࣋ͬͯΔͷͰɺαʔόʔىಈ࣌͜ͷϝιουΛ࣮ߦ
•ىಈ࣌ʹࣗಈతʹapplication.confͱ͍͏ઃఆϑΝΠϧΛಡΈࠐΈɺͦͷઃఆ
༰ʹΑͬͯىಈ࣌ͷॲཧΛܾఆ
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EngineMain
• ར༻͢ΔػೳɺApplicationΫϥεͷ֦ுؔʹͯఆٛ͢Δ
fun Application.module() {
install(Routing) {
get("/") {
call.respondText("Hello World!")
}
}
}
Application.kt
͜ͷϝιου໊ͳΜͰ͍͍
installϝιουΛՃ͍ͯ͘͜͠ͱͰɺඞཁͳػೳΛ͖ʹΈࠐΊΔ
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EngineMain
• ઃఆϑΝΠϧapplication.confʹɺىಈͷઃఆใΛهड़
ktor {
deployment {
port = 8080
}
application {
modules = [ ApplicationKt.module ]
}
}
application.conf
(ύοέʔδ໊.)Ϋϥε໊(ϑΝΠϧ໊ͷඌʹKtΛ͚ͭΔ).֦ு໊ؔ
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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Routing
• RoutingΛinstall͢Δ͜ͱͰɺrouteొ͕Ͱ͖Δ
• call.parameters͔ΒϦΫΤετύϥϝʔλύεύϥϝʔλ
ΛऔಘՄೳʢͨͩ͠ܕͯ͢StringʹͳΔʣ
fun Application.module() {
install(Routing) {
get("/users/{userId}") {
// ܕඞͣStringͳͷͰඞཁʹԠͯ͡Ωϟετ͢Δ
val userId = call.parameters["userId"].toLong()
}
}
}
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ͬͱλΠϓηʔϑʹ
ύϥϝʔλʔΛѻ͍͍ͨ
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Locations
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Locations(※ݱࡏ·ͩexperimental)
• ύϥϝʔλΛλΠϓηʔϑʹѻ͑Δ
• Int, Long, Float, Double, Boolean, String, enum͕༻Մೳ
@Location("/users/{userId}")
data class UserLocation(val userId: Long)
fun Application.module() {
install(Locations)
install(Routing) {
get { param ->
// paramUserLocationܕʹͳΔͷͰɺuserIdΛͦͷ··LongܕͰऔಘͰ͖Δ
val userId = param.userId
}
}
}
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LocationͷωετͰ͖Δ
@Location("/users/{userId}")
data class UserLocation(val userId: Long) {
@Location("/email")
data class EmailLocation(val userLocation: UserLocation)
}
• ؔ࿈ͨ͠routeΛ·ͱΊΒΕΔͷϝϦοτ͕ͩɺ͕૿͑ͯ͘
Δͱͪ͝Όͪ͝Όͯ͠Θ͔ΓͮΒ͘ͳΔ
• ʮKtorͷRoutingఆٛͷϕετϓϥΫςΟεΛߟ͑ͯΈΔʯʹৄ
͘͠ॻ͖·ͨ͠ʢͪͳΈʹલ৬ͷTechϒϩάʣ
https://tech.bizreach.co.jp/posts/324/ktor-routing/
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͏Ұาલ
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ϓϦϛςΟϒҎ֎ͷܕͷࣗಈม
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ͨͱ͑ValueObject
• ͜Μͳײ͡ͰɺValueObjectࣗಈͰมͰ͖Δͱศར
data class UserId(val userId: Long)
@Location("/users/{userId}")
data class UserLocation(val userId: UserId)
fun Application.module() {
install(Locations)
install(Routing) {
get { param ->
val userId = param.userId // UserIdܕͰͦͷ··औಘͰ͖Δʂ
}
}
}
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DataConversionΛ͏ͱͰ͖·͢
fun Application.module() {
install(DataConversion) {
convert {
decode { values, _ ->
values.singleOrNull()?.let { UserId(it.toLong()) }
}
encode { id ->
when (id) {
is UserId -> listOf(id.value.toString())
else -> throw DataConversionException("Can not convert.")
}
}
}
}
}
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ͿͬͪΌ͚ɺSpringBootͱൺͯͲ͏ʁ
• ֤Controllerʹ͚ͭΔ@RequestMapping
ΞϊςʔγϣϯʹrouteΛهࡌ͢Δํࣜ
• ͕૿͑Δͱʮ͜ͷAPIɺͲ͜ͷ
ControllerݺΜͰΔΜ͚ͩͬʯ͕୳ͮ͠
Β͍
SpringBoot Ktor
• routeΛ·ͱΊͯఆٛ͢Δํࣜ
• LocationsΛΘͳ͍ͱλΠϓηʔϑʹ
ѻ͑ͳͯͭ͘ΒΈ
• LocationsఆٛͷํΛؾΛ͚ͭͳ͍
ͱΊͬͪΌಡΈͮΒ͘ͳΔ
ҰҰɻݸਓతʹKtorͷΓํͷ΄͏͕͖͕ͩɺ
Locationsͷ͍উखΛ͏গ͠վળͯ͠΄͍͠
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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ೝূॲཧ
• ϕʔγοΫೝূ / Digestೝূ / JWT / LDAPೝূ / OAuthΛαϙʔτɻ
• install(Authentication)͢Εར༻Մೳʢ௨ৗͷktorҎ֎ʹktor_authΛ
dependenciesʹՃ͢Δ͜ͱ͕ඞཁʣ
• Routingఆٛʹͯೝূ͕ඞཁͳrouteʹରͯ͠authenticate{}ϒϩοΫͰғΉͱɺ
ೝূ͕௨͍ͬͯΔ߹͚ͩॲཧΛ࣮ߦ͢Δ͜ͱ͕Մೳɻ
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Routingଆ
fun Application.module() {
install(Routing) {
// ͜͜ೝূෆཁ
post(“/login") { // ϩάΠϯॲཧɻޭ࣌ʹtokenΛੜͯ͠ฦ٫ }
authenticate {
// ͜ͷϒϩοΫೝূ͕௨ͬͯͳ͍ͱ࣮ߦͰ͖ͳ͍
get("/users/{userId}") {
// ͜ΕͰϩάΠϯϢʔβʔͷใΛऔಘͰ͖Δ
val user = authentication.principal()!!
...
}
}
}
}
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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DIʹ͍ͭͯ
• DIࣗମKtorͷػೳͱͯ͠ఏڙ͞Ε͍ͯͳ͍ͷͰɺ͖ͳϥ
ΠϒϥϦΛ͍͍ͬͯ
• KtorͷެࣜϖʔδʹKodeinΛͬͨαϯϓϧ͕͋Δ
• KoinࣗલͰKtor༻ʹApplication.installͰ͖ΔFeatureΛఏڙ͠
͓ͯΓɺ͜ΕΛ͏ͱKtorىಈ࣌ʹࣗಈͰDIίϯςφΛى
ಈͯ͘͠ΕΔ
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KoinΛͬͨྫ
fun Application.module() {
install(Koin) {
modules(
module {
single { UserController() }
}
)
}
install(Routing) {
val userController: UserController by inject()
get("users") {
call.respond(userController.find())
}
}
}
͜ͷதͰDI͢ΔϞδϡʔϧΛఆ͓ٛͯ͘͠ͱ
औಘॲཧΛinject()ʹҠৡ͢Δ͜ͱͰΦϒδΣΫτ͕औಘͰ͖Δʂ
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AGENDA
• Server-Side Kotlinͷݱঢ়
• ٕज़બఆͷϙΠϯτɿͳͥKtorΛબΜͩͷ͔ʁ
• ࣮ફKtor
• ىಈͷํ๏
• Routing
• ೝূ
• DI
• Testing
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TestEngine
• Ktorʹ༻ҙ͞Ε͍ͯΔɺԾతʹαʔόʔΛىಈ͢ΔͨΊͷςετ༻
Engine
• ىಈ࣌withTestApplication()Λ༻͢Δ
• ࣮ࡍͷHTTPϦΫΤετड͚͚ͳ͍͕ɺٙࣅϦΫΤετΛඈ͢͜ͱ
ʹΑͬͯఆٛͨ͠routeΛݺͼग़͢͜ͱ͕Ͱ͖Δ
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TestEngineͷ༻ྫ
withTestApplication(Application::module) {
handleRequest(HttpMethod.Post, "/login") {
addHeader(HttpHeaders.ContentType,
ContentType.Application.FormUrlEncoded.toString())
setBody(listOf(
"email" to "[email protected]",
"password" to "loginPass"
).formUrlEncode())
}.apply {
assertThat(response.status()).isEqualTo(HttpStatusCode.OK)
}
}
ىಈ͢ΔΞϓϦέʔγϣϯͷϝιουΛࢦఆ
Httpϝιουͱpathͷࢦఆ
HeaderͱBodyͷࢦఆ
handleRequestͷΓTestApplicationCallܕ͕
ϓϩύςΟͱͯ͠responseΛอ͍࣋ͯ͠Δ
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MockKͱKoinΛͬͨMocking
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ͨͱ͑ɺ͜͏͍͏ॲཧΛ୯ମͰςετ͢Δʹʁ
install(Routing) {
val userController: UserController by inject()
@Location("/users/{userId}")
data class UserLocation(val userId: UserId)
get {
call.respond(userController.find(userId))
}
}
͍ͭ͜ΛMockԽ͍ͨ͠
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MockKͱKoin
val userController = mockk(relaxed = true)
val module = module { single { userController } }
@Test
fun `Return user data when called request with user id`() {
val userId = UserId(1)
every { userController.find(userId) } returns UserData(1, "ࢁాଠ")
withTestApplication(Application::module) {
startKoin { modules(module) }
handleRequest(HttpMethod.Get, "/users/1").apply {
assertThat(response.status()).isEqualTo(HttpStatusCode.OK)
…
}
}
}
MockΦϒδΣΫτΛ࡞͠ɺKoinϞδϡʔϧʹొ
MockΦϒδΣΫτ͕ݺΕͨ࣌ͷڍಈΛఆٛ
KoinΛىಈ
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ᘳɾɾɾͱࢥ͍͖
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ౖΒΕͨ
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ͳΜͰʁ
• Application.moduleͰinstall(Koin)͢Δͱɺىಈ࣌ʹࣗಈతʹstartKoin͕ݺΕΔ
fun Application.module() {
install(Koin) {
modules(
module {
single { UserController() }
}
)
}
}
• TestEngineͰԾతʹKtorΛىಈ͍ͯ͠ΔͨΊɺಉ͡Α͏ʹstartKoin͕Δ
• MockΦϒδΣΫτΛΠϯδΣΫτ͢ΔͨΊʹstartKoin͢ΔͱೋॏىಈʹͳΔ
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ͱ͍͏͜ͱͰɺ1ߦՃ
val userController = mockk(relaxed = true)
val module = module { single { userController } }
@Test
fun `Return user data when called request with user id`() {
val userId = UserId(1)
every { userController.find(userId) } returns UserData(1, "ࢁాଠ")
withTestApplication(Application::module) {
stopKoin()
startKoin { modules(module) }
handleRequest(HttpMethod.Get, "/users/1").apply {
assertThat(response.status()).isEqualTo(HttpStatusCode.OK)
…
}
}
}
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࠶࣮ߦ
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Let’s enjoy Server-Side Kotlin and Ktor!!
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࠷ޙʹએ
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WE ARE HIRING!!
• Server side: Kotlin(Ktor)
• Front: Nuxt.js, Typescript
• Backend: Go
• ࣄۀ༰ɿ๏ਓ͚VISAΧʔυΛͬͨBtoBαʔϏεʢৄࡉۙެ։ʣ
• ෭ۀܴ(Քಇि2ఔʙOKʣ
• ϑϧϦϞʔτOKʢΦϑΟεຊʣ
• ͪΐͬͱͰؾʹͳΔਓ࠙ձɺ͘͠Twitterʹͯ@kaonash_·Ͱʂ
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Thank you!!