feat(i18n): AWS 언어 감지와 분할 번역 공급자를 추가한다

build.gradle.kts

@@ -16,6 +16,8 @@ plugins {
 group = "kr.co.vividnext"
 version = "0.0.1-SNAPSHOT"
 val querydslVersion = "5.0.0"
+extra["httpclient5.version"] = "5.6.4"
+extra["httpcore5.version"] = "5.4.3"
 
 java {
     sourceCompatibility = JavaVersion.VERSION_17
@@ -56,6 +58,10 @@ dependencies {
     implementation("com.amazonaws:aws-java-sdk-s3:1.12.380")
     implementation("com.amazonaws:aws-java-sdk-cloudfront:1.12.380")
 
+    implementation(platform("software.amazon.awssdk:bom:2.57.11"))
+    implementation("software.amazon.awssdk:comprehend")
+    implementation("software.amazon.awssdk:translate")
+
     // bootpay
     implementation("io.github.bootpay:backend:2.2.1")
 

src/main/kotlin/kr/co/vividnext/sodalive/i18n/translation/AwsLanguageDetectionProvider.kt

@@ -0,0 +1,27 @@
+package kr.co.vividnext.sodalive.i18n.translation
+
+import org.springframework.stereotype.Component
+import software.amazon.awssdk.services.comprehend.ComprehendClient
+import software.amazon.awssdk.services.comprehend.model.DetectDominantLanguageRequest
+
+@Component
+class AwsLanguageDetectionProvider(private val client: ComprehendClient) : LanguageDetectionProvider {
+    override val providerId = LanguageProviderId.AWS
+
+    override fun detect(query: String): String? {
+        if (query.isBlank()) return null
+
+        return try {
+            // shortcut: 감지는 앞 100000 UTF-8 바이트만 판정하므로 전체 본문과 결과가 다를 수 있음, 전체 본문 기준 품질이 요구되면 별도 감지 정책 승인 후 업그레이드
+            val text = takeTextPrefixByCodePoint(query, MAX_REQUEST_TEXT_BYTES, ::utf8CodePointSize)
+            val request = DetectDominantLanguageRequest.builder().text(text).build()
+            client.detectDominantLanguage(request).languages().firstOrNull()?.languageCode()?.takeIf { it.isNotBlank() }
+        } catch (_: Exception) {
+            null
+        }
+    }
+
+    companion object {
+        private const val MAX_REQUEST_TEXT_BYTES = 100000
+    }
+}

src/main/kotlin/kr/co/vividnext/sodalive/i18n/translation/AwsLanguageProviderConfiguration.kt

@@ -0,0 +1,32 @@
+package kr.co.vividnext.sodalive.i18n.translation
+
+import org.springframework.beans.factory.annotation.Value
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+import software.amazon.awssdk.auth.credentials.AwsBasicCredentials
+import software.amazon.awssdk.auth.credentials.StaticCredentialsProvider
+import software.amazon.awssdk.regions.Region
+import software.amazon.awssdk.services.comprehend.ComprehendClient
+import software.amazon.awssdk.services.translate.TranslateClient
+
+@Configuration
+class AwsLanguageProviderConfiguration(
+    @Value("\${cloud.aws.credentials.access-key}") accessKey: String,
+    @Value("\${cloud.aws.credentials.secret-key}") secretKey: String,
+    @Value("\${cloud.aws.region.static}") region: String
+) {
+    private val credentialsProvider = StaticCredentialsProvider.create(AwsBasicCredentials.create(accessKey, secretKey))
+    private val region = Region.of(region)
+
+    @Bean(destroyMethod = "close")
+    fun comprehendClient(): ComprehendClient = ComprehendClient.builder()
+        .credentialsProvider(credentialsProvider)
+        .region(region)
+        .build()
+
+    @Bean(destroyMethod = "close")
+    fun translateClient(): TranslateClient = TranslateClient.builder()
+        .credentialsProvider(credentialsProvider)
+        .region(region)
+        .build()
+}

src/main/kotlin/kr/co/vividnext/sodalive/i18n/translation/AwsTranslationService.kt

@@ -0,0 +1,48 @@
+package kr.co.vividnext.sodalive.i18n.translation
+
+import org.springframework.stereotype.Service
+import software.amazon.awssdk.services.translate.TranslateClient
+import software.amazon.awssdk.services.translate.model.TranslateTextRequest
+
+@Service
+class AwsTranslationService(private val client: TranslateClient) : TranslationProvider {
+    override val providerId = LanguageProviderId.AWS
+    override val providerVersion = "translate-2017-07-01"
+
+    override fun translate(request: TranslateRequest): TranslateResult {
+        if (request.texts.isEmpty() || request.sourceLanguage == request.targetLanguage) {
+            return TranslateResult(emptyList())
+        }
+        if (
+            !TranslationLanguages.isSupported(request.sourceLanguage) ||
+            !TranslationLanguages.isSupported(request.targetLanguage)
+        ) {
+            return TranslateResult(emptyList())
+        }
+
+        val translatedTexts = mutableListOf<String>()
+        try {
+            for (text in request.texts) {
+                val translatedText = StringBuilder()
+                for (chunk in splitTextByCodePoint(text, MAX_REQUEST_TEXT_BYTES, ::utf8CodePointSize)) {
+                    val sdkRequest = TranslateTextRequest.builder()
+                        .sourceLanguageCode(request.sourceLanguage)
+                        .targetLanguageCode(request.targetLanguage)
+                        .text(chunk)
+                        .build()
+                    val translated = client.translateText(sdkRequest)?.translatedText()
+                    if (translated.isNullOrBlank()) return TranslateResult(emptyList())
+                    translatedText.append(translated)
+                }
+                translatedTexts.add(translatedText.toString())
+            }
+        } catch (_: Exception) {
+            return TranslateResult(emptyList())
+        }
+        return TranslateResult(translatedTexts)
+    }
+
+    companion object {
+        private const val MAX_REQUEST_TEXT_BYTES = 10000
+    }
+}

src/test/kotlin/kr/co/vividnext/sodalive/i18n/translation/AwsLanguageDetectionProviderTest.kt

@@ -0,0 +1,134 @@
+package kr.co.vividnext.sodalive.i18n.translation
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertNull
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.MethodSource
+import org.junit.jupiter.params.provider.NullAndEmptySource
+import org.junit.jupiter.params.provider.ValueSource
+import org.mockito.ArgumentCaptor
+import org.mockito.Mockito
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.boot.test.context.SpringBootTest
+import org.springframework.boot.test.mock.mockito.MockBean
+import org.springframework.boot.test.system.CapturedOutput
+import org.springframework.boot.test.system.OutputCaptureExtension
+import software.amazon.awssdk.core.exception.SdkClientException
+import software.amazon.awssdk.services.comprehend.ComprehendClient
+import software.amazon.awssdk.services.comprehend.model.DetectDominantLanguageRequest
+import software.amazon.awssdk.services.comprehend.model.DetectDominantLanguageResponse
+import software.amazon.awssdk.services.comprehend.model.DominantLanguage
+import java.util.stream.Stream
+
+@SpringBootTest(classes = [AwsLanguageDetectionProvider::class], webEnvironment = SpringBootTest.WebEnvironment.NONE)
+@ExtendWith(OutputCaptureExtension::class)
+class AwsLanguageDetectionProviderTest @Autowired constructor(
+    private val provider: AwsLanguageDetectionProvider
+) {
+    @MockBean
+    private lateinit var client: ComprehendClient
+
+    @ParameterizedTest
+    @ValueSource(strings = ["hi", " 안녕\t\n", "\uD83D\uDE00"])
+    @DisplayName("짧은 원문도 공백 변경 없이 감지하고 첫 후보를 반환한다")
+    fun shouldSendShortTextUnchangedAndUseFirstCandidate(query: String) {
+        respond(language("ja", 0.1f), language("en", 0.9f))
+
+        assertEquals("ja", provider.detect(query))
+        assertEquals(LanguageProviderId.AWS, provider.providerId)
+        assertRequestedText(query)
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = ["", " ", "\t\n"])
+    @DisplayName("빈 감지 입력과 공백은 SDK를 호출하지 않는다")
+    fun shouldSkipBlankText(query: String) {
+        assertNull(provider.detect(query))
+        Mockito.verifyNoInteractions(client)
+    }
+
+    @ParameterizedTest
+    @MethodSource("prefixCases")
+    @DisplayName("감지 입력을 100000 UTF-8 바이트 이내의 정확한 code point prefix로 제한한다")
+    fun shouldSendExactCodePointPrefix(query: String, expected: String) {
+        respond(language("ko", 0.8f))
+
+        assertEquals("ko", provider.detect(query))
+        assertRequestedText(expected)
+    }
+
+    @Test
+    @DisplayName("낮은 confidence의 미지원 첫 언어 코드도 그대로 반환한다")
+    fun shouldAcceptUnsupportedFirstLanguageWithoutConfidenceThreshold() {
+        respond(language("fr", 0.001f), language("en", 0.999f))
+
+        assertEquals("fr", provider.detect("bonjour"))
+        assertRequestedText("bonjour")
+    }
+
+    @ParameterizedTest
+    @NullAndEmptySource
+    @ValueSource(strings = [" \t\n"])
+    @DisplayName("첫 후보 코드가 없거나 공백이면 유효한 후속 후보도 선택하지 않는다")
+    fun shouldRejectInvalidFirstCandidateWithoutScanningLaterCandidates(code: String?) {
+        respond(language(code, 0.9f), language("en", 0.8f))
+
+        assertNull(provider.detect("source"))
+        assertRequestedText("source")
+    }
+
+    @Test
+    @DisplayName("감지 후보 목록이 없으면 null을 반환한다")
+    fun shouldReturnNullForMissingCandidates() {
+        respond()
+
+        assertNull(provider.detect("source"))
+        assertRequestedText("source")
+    }
+
+    @Test
+    @DisplayName("SDK 실패는 원문과 오류를 로그에 노출하지 않고 null로 변환한다")
+    fun shouldReturnNullWithoutLeakingSdkFailure(output: CapturedOutput) {
+        Mockito.`when`(client.detectDominantLanguage(Mockito.any(DetectDominantLanguageRequest::class.java)))
+            .thenThrow(SdkClientException.create("sensitive-sdk-marker"))
+
+        assertNull(provider.detect("sensitive-source-marker"))
+        assertRequestedText("sensitive-source-marker")
+        assertFalse(output.all.contains("sensitive-sdk-marker"))
+        assertFalse(output.all.contains("sensitive-source-marker"))
+    }
+
+    private fun respond(vararg languages: DominantLanguage) {
+        Mockito.`when`(client.detectDominantLanguage(Mockito.any(DetectDominantLanguageRequest::class.java)))
+            .thenReturn(DetectDominantLanguageResponse.builder().languages(*languages).build())
+    }
+
+    private fun language(code: String?, score: Float): DominantLanguage {
+        return DominantLanguage.builder().languageCode(code).score(score).build()
+    }
+
+    private fun assertRequestedText(expected: String) {
+        val captor = ArgumentCaptor.forClass(DetectDominantLanguageRequest::class.java)
+        Mockito.verify(client).detectDominantLanguage(captor.capture())
+        assertEquals(expected, captor.value.text())
+        Mockito.verifyNoMoreInteractions(client)
+    }
+
+    companion object {
+        @JvmStatic
+        fun prefixCases(): Stream<Arguments> = Stream.of(
+            Arguments.of("a".repeat(100000), "a".repeat(100000)),
+            Arguments.of("가".repeat(33333) + "x", "가".repeat(33333) + "x"),
+            Arguments.of("\uD83D\uDE00".repeat(25000), "\uD83D\uDE00".repeat(25000)),
+            Arguments.of("a".repeat(100000) + "excluded-tail", "a".repeat(100000)),
+            Arguments.of("a".repeat(99999) + "가tail", "a".repeat(99999)),
+            Arguments.of("a".repeat(99998) + "\uD83D\uDE00tail", "a".repeat(99998)),
+            Arguments.of("a".repeat(99996) + "\uD83D\uDE00tail", "a".repeat(99996) + "\uD83D\uDE00")
+        )
+    }
+}

src/test/kotlin/kr/co/vividnext/sodalive/i18n/translation/AwsLanguageProviderConfigurationTest.kt

@@ -0,0 +1,127 @@
+package kr.co.vividnext.sodalive.i18n.translation
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertNotNull
+import org.junit.jupiter.api.Assertions.assertNull
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.CsvSource
+import org.junit.jupiter.params.provider.ValueSource
+import org.springframework.boot.test.context.ConfigDataApplicationContextInitializer
+import org.springframework.boot.test.context.runner.ApplicationContextRunner
+import org.springframework.test.util.ReflectionTestUtils
+import software.amazon.awssdk.auth.credentials.StaticCredentialsProvider
+import software.amazon.awssdk.awscore.AwsClient
+import software.amazon.awssdk.core.client.config.SdkClientConfiguration
+import software.amazon.awssdk.core.client.config.SdkClientOption
+import software.amazon.awssdk.regions.Region
+import software.amazon.awssdk.services.comprehend.ComprehendClient
+import software.amazon.awssdk.services.translate.TranslateClient
+
+class AwsLanguageProviderConfigurationTest {
+    @Test
+    @DisplayName("공용 테스트 YAML의 합성 키와 서울 리전으로 실제 AWS clients와 providers를 생성한다")
+    fun shouldLoadRealClientsAndProvidersFromSharedTestConfiguration() {
+        ApplicationContextRunner()
+            .withInitializer(ConfigDataApplicationContextInitializer())
+            .withUserConfiguration(
+                AwsLanguageProviderConfiguration::class.java,
+                AwsLanguageDetectionProvider::class.java,
+                AwsTranslationService::class.java
+            )
+            .run { context ->
+                assertNull(context.startupFailure)
+                assertEquals(1, context.getBeansOfType(ComprehendClient::class.java).size)
+                assertEquals(1, context.getBeansOfType(TranslateClient::class.java).size)
+                assertEquals(1, context.getBeansOfType(LanguageDetectionProvider::class.java).size)
+                assertEquals(1, context.getBeansOfType(TranslationProvider::class.java).size)
+                assertEquals(LanguageProviderId.AWS, context.getBean(AwsLanguageDetectionProvider::class.java).providerId)
+                assertEquals(LanguageProviderId.AWS, context.getBean(AwsTranslationService::class.java).providerId)
+                val clients = listOf(
+                    context.getBean(ComprehendClient::class.java),
+                    context.getBean(TranslateClient::class.java)
+                )
+                clients.forEach { client ->
+                    val configuration = client.serviceClientConfiguration()
+                    assertEquals(Region.AP_NORTHEAST_2, configuration.region())
+                    assertTrue(configuration.credentialsProvider() is StaticCredentialsProvider)
+                    val credentials = (configuration.credentialsProvider() as StaticCredentialsProvider).resolveCredentials()
+                    assertEquals("test-access-key", credentials.accessKeyId())
+                    assertEquals("test-secret-key", credentials.secretAccessKey())
+                }
+            }
+    }
+
+    @ParameterizedTest
+    @CsvSource(
+        "'',synthetic-secret-key,Access key ID cannot be blank.",
+        "synthetic-access-key,'',Secret access key cannot be blank."
+    )
+    @DisplayName("운영 AWS 설정은 access key 또는 secret key가 비어 있으면 시작을 거부한다")
+    fun shouldRejectBlankCredentialsAtStartup(accessKey: String, secretKey: String, expectedMessage: String) {
+        ApplicationContextRunner()
+            .withUserConfiguration(AwsLanguageProviderConfiguration::class.java)
+            .withPropertyValues(
+                "cloud.aws.credentials.access-key=$accessKey",
+                "cloud.aws.credentials.secret-key=$secretKey",
+                "cloud.aws.region.static=ap-northeast-2"
+            )
+            .run { context ->
+                assertNotNull(context.startupFailure)
+                val rootCause = generateSequence(context.startupFailure) { it.cause }.last()
+                assertTrue(rootCause is NullPointerException)
+                assertEquals(expectedMessage, rootCause.message)
+            }
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = ["ap-northeast-2", "eu-west-1"])
+    @DisplayName("기존 명시 설정으로 실제 동기 SDK clients를 생성하고 Spring 종료 시 둘 다 닫는다")
+    fun shouldConfigureRealClientsAndCloseThemAtShutdown(region: String) {
+        val poolClosedChecks = mutableListOf<() -> Boolean>()
+        ApplicationContextRunner()
+            .withUserConfiguration(AwsLanguageProviderConfiguration::class.java)
+            .withPropertyValues(
+                "cloud.aws.credentials.access-key=synthetic-access-key",
+                "cloud.aws.credentials.secret-key=synthetic-secret-key",
+                "cloud.aws.region.static=$region"
+            )
+            .run { context ->
+                assertNull(context.startupFailure)
+                assertEquals(1, context.getBeansOfType(ComprehendClient::class.java).size)
+                assertEquals(1, context.getBeansOfType(TranslateClient::class.java).size)
+                val clients = listOf(
+                    context.getBean(ComprehendClient::class.java),
+                    context.getBean(TranslateClient::class.java)
+                )
+                clients.forEach { client ->
+                    val configuration = client.serviceClientConfiguration()
+                    assertEquals(Region.of(region), configuration.region())
+                    assertTrue(configuration.credentialsProvider() is StaticCredentialsProvider)
+                    val credentials = (configuration.credentialsProvider() as StaticCredentialsProvider).resolveCredentials()
+                    assertEquals("synthetic-access-key", credentials.accessKeyId())
+                    assertEquals("synthetic-secret-key", credentials.secretAccessKey())
+                    val isClosed = connectionPoolClosedCheck(client)
+                    assertFalse(isClosed())
+                    poolClosedChecks.add(isClosed)
+                }
+            }
+        assertEquals(2, poolClosedChecks.size)
+        poolClosedChecks.forEach { assertTrue(it()) }
+    }
+
+    private fun connectionPoolClosedCheck(client: AwsClient): () -> Boolean {
+        val configuration = ReflectionTestUtils.getField(client, "clientConfiguration") as SdkClientConfiguration
+        val httpClient = configuration.option(SdkClientOption.SYNC_HTTP_CLIENT)
+        val apacheClient = requireNotNull(ReflectionTestUtils.getField(httpClient, "httpClient"))
+        val connectionManager = requireNotNull(
+            ReflectionTestUtils.invokeMethod<Any>(apacheClient, "getHttpClientConnectionManager")
+        )
+        return {
+            requireNotNull(ReflectionTestUtils.invokeMethod<Boolean>(connectionManager, "isClosed"))
+        }
+    }
+}

src/test/kotlin/kr/co/vividnext/sodalive/i18n/translation/AwsTranslationServiceTest.kt

@@ -0,0 +1,209 @@
+package kr.co.vividnext.sodalive.i18n.translation
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.extension.ExtendWith
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.CsvSource
+import org.junit.jupiter.params.provider.ValueSource
+import org.mockito.Mockito
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.boot.test.context.SpringBootTest
+import org.springframework.boot.test.mock.mockito.MockBean
+import org.springframework.boot.test.system.CapturedOutput
+import org.springframework.boot.test.system.OutputCaptureExtension
+import software.amazon.awssdk.core.exception.SdkClientException
+import software.amazon.awssdk.services.translate.TranslateClient
+import software.amazon.awssdk.services.translate.model.TranslateTextRequest
+import software.amazon.awssdk.services.translate.model.TranslateTextResponse
+
+@SpringBootTest(classes = [AwsTranslationService::class], webEnvironment = SpringBootTest.WebEnvironment.NONE)
+@ExtendWith(OutputCaptureExtension::class)
+class AwsTranslationServiceTest @Autowired constructor(
+    private val service: AwsTranslationService
+) {
+    @MockBean
+    private lateinit var client: TranslateClient
+    private val requests = mutableListOf<TranslateTextRequest>()
+
+    @BeforeEach
+    fun setUp() {
+        requests.clear()
+    }
+
+    @ParameterizedTest
+    @ValueSource(ints = [12, 10000])
+    @DisplayName("10000 UTF-8 바이트 이하 원문은 한 번 요청하고 AWS 결과를 반환한다")
+    fun shouldTranslateTextWithinByteLimit(length: Int) {
+        respondWith { response("translated") }
+        val source = "a".repeat(length)
+
+        assertEquals(listOf("translated"), translate(source).translatedText)
+        assertEquals(LanguageProviderId.AWS, service.providerId)
+        assertEquals("translate-2017-07-01", service.providerVersion)
+        assertRequests(source)
+    }
+
+    @Test
+    @DisplayName("10001바이트 원문을 순서대로 나누고 구분자 없이 결합한다")
+    fun shouldSplitTextOverByteLimitAndJoinWithoutSeparator() {
+        val first = "a".repeat(10000)
+        respondWith { response(if (it.text() == first) "first " else "tail") }
+
+        assertEquals(listOf("first tail"), translate(first + "b").translatedText)
+        assertRequests(first, "b")
+    }
+
+    @Test
+    @DisplayName("한글 code point와 공백을 UTF-8 한도에 맞춰 손실 없이 분할한다")
+    fun shouldPreserveKoreanAndWhitespaceAcrossChunks() {
+        val first = "가".repeat(3333) + "\n"
+        val second = " 나\t"
+        respondWith { response(if (it.text() == first) "first" else "second") }
+
+        assertEquals(listOf("firstsecond"), translate(first + second).translatedText)
+        assertRequests(first, second)
+    }
+
+    @Test
+    @DisplayName("경계에 걸친 보조 평면 문자를 다음 조각에 함께 보존한다")
+    fun shouldKeepSupplementaryCodePointTogetherAtBoundary() {
+        val first = "a".repeat(9998)
+        val second = "\uD83D\uDE00b"
+        respondWith { response(if (it.text() == first) "first" else "second") }
+
+        assertEquals(listOf("firstsecond"), translate(first + second).translatedText)
+        assertRequests(first, second)
+    }
+
+    @Test
+    @DisplayName("정확히 10000바이트인 보조 평면 원문은 분할하지 않는다")
+    fun shouldKeepExactSupplementaryByteLimitInOneRequest() {
+        val source = "\uD83D\uDE00".repeat(2500)
+        respondWith { response("translated") }
+
+        assertEquals(listOf("translated"), translate(source).translatedText)
+        assertRequests(source)
+    }
+
+    @Test
+    @DisplayName("여러 원문의 조각을 순차 호출하고 입력 순서대로 원문당 결과 하나를 반환한다")
+    fun shouldReturnOneJoinedOutputPerOriginalInOrder() {
+        val first = "a".repeat(10000)
+        val second = "b".repeat(10000)
+        val translated = listOf("first-", "tail", "second-", "tail")
+        respondWith { response(translated[requests.size - 1]) }
+
+        assertEquals(listOf("first-tail", "second-tail"), translate(first + "a", second + "b").translatedText)
+        assertRequests(first, "a", second, "b")
+    }
+
+    @ParameterizedTest
+    @CsvSource("ko,en", "en,ja", "ja,ko")
+    @DisplayName("기존 지원 언어의 source와 target을 SDK 요청에 명시한다")
+    fun shouldSendExplicitSupportedLanguages(source: String, target: String) {
+        respondWith { response("translated") }
+
+        assertEquals(listOf("translated"), service.translate(TranslateRequest(listOf("source"), source, target)).translatedText)
+        assertEquals(1, requests.size)
+        assertEquals("source", requests.single().text())
+        assertEquals(source, requests.single().sourceLanguageCode())
+        assertEquals(target, requests.single().targetLanguageCode())
+    }
+
+    @ParameterizedTest
+    @CsvSource(
+        "middle,exception", "middle,null-response", "middle,missing-text", "middle,empty", "middle,blank",
+        "later,exception", "later,null-response", "later,missing-text", "later,empty", "later,blank"
+    )
+    @DisplayName("중간 조각이나 다음 원문의 실패는 앞선 성공을 폐기하고 후속 호출을 중단한다")
+    fun shouldDiscardEntireRequestAndStopAfterAnyFailure(position: String, failure: String, output: CapturedOutput) {
+        val first = "a".repeat(10000)
+        val broken = "b".repeat(10000)
+        val failingText = if (position == "middle") broken else "sensitive-source-marker"
+        respondWith {
+            if (it.text() != failingText) {
+                response("partial success")
+            } else {
+                when (failure) {
+                    "exception" -> throw SdkClientException.create("sensitive-sdk-marker")
+                    "null-response" -> null
+                    "missing-text" -> response(null)
+                    "empty" -> response("")
+                    else -> response(" \t\n")
+                }
+            }
+        }
+        val texts = if (position == "middle") {
+            listOf("earlier", first + broken + "c", "later")
+        } else {
+            listOf("earlier", failingText, "later")
+        }
+
+        assertEquals(emptyList<String>(), service.translate(TranslateRequest(texts, "ko", "en")).translatedText)
+        if (position == "middle") assertRequests("earlier", first, broken) else assertRequests("earlier", failingText)
+        assertFalse(output.all.contains("sensitive-sdk-marker"))
+        assertFalse(output.all.contains("sensitive-source-marker"))
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = ["", " \t\n"])
+    @DisplayName("빈 raw 문자열과 공백도 원문 그대로 SDK에 전달한다")
+    fun shouldPreserveEmptyAndWhitespaceRawText(source: String) {
+        respondWith { response("translated") }
+
+        assertEquals(listOf("translated"), translate(source).translatedText)
+        assertRequests(source)
+    }
+
+    @Test
+    @DisplayName("빈 원문 목록이면 SDK를 호출하지 않는다")
+    fun shouldSkipEmptyList() {
+        assertEquals(emptyList<String>(), translate().translatedText)
+        Mockito.verifyNoInteractions(client)
+    }
+
+    @Test
+    @DisplayName("같은 언어이면 SDK를 호출하지 않는다")
+    fun shouldSkipSameLanguage() {
+        assertEquals(emptyList<String>(), service.translate(TranslateRequest(listOf("source"), "ko", "ko")).translatedText)
+        Mockito.verifyNoInteractions(client)
+    }
+
+    @ParameterizedTest
+    @CsvSource("fr,en", "ko,fr", "auto,en")
+    @DisplayName("미지원 source 또는 target이면 SDK를 호출하지 않는다")
+    fun shouldSkipUnsupportedLanguage(source: String, target: String) {
+        assertEquals(emptyList<String>(), service.translate(TranslateRequest(listOf("source"), source, target)).translatedText)
+        Mockito.verifyNoInteractions(client)
+    }
+
+    private fun translate(vararg texts: String): TranslateResult {
+        return service.translate(TranslateRequest(texts.toList(), "ko", "en"))
+    }
+
+    private fun respondWith(handler: (TranslateTextRequest) -> TranslateTextResponse?) {
+        Mockito.`when`(client.translateText(Mockito.any(TranslateTextRequest::class.java))).thenAnswer {
+            val request = it.getArgument<TranslateTextRequest>(0)
+            requests.add(request)
+            handler(request)
+        }
+    }
+
+    private fun response(text: String?): TranslateTextResponse {
+        return TranslateTextResponse.builder().sourceLanguageCode("ko").targetLanguageCode("en").translatedText(text).build()
+    }
+
+    private fun assertRequests(vararg texts: String) {
+        assertEquals(texts.toList(), requests.map { it.text() })
+        requests.forEach {
+            assertEquals("ko", it.sourceLanguageCode())
+            assertEquals("en", it.targetLanguageCode())
+        }
+        Mockito.verify(client, Mockito.times(texts.size)).translateText(Mockito.any(TranslateTextRequest::class.java))
+        Mockito.verifyNoMoreInteractions(client)
+    }
+}

src/test/resources/application.yml

@@ -78,8 +78,8 @@ cloud:
 
     aws:
         credentials:
-            accessKey: ""
+            accessKey: "test-access-key"
-            secretKey: ""
+            secretKey: "test-secret-key"
         s3:
             contentBucket: ""
             bucket: ""