test: BannerService/S3Service 단위 테스트 추가 + 이미지 업로드 크래시 버그 2건 수정

src/main/java/org/runnect/server/external/aws/S3Service.java

@@ -70,21 +70,27 @@ private String createFileName(String fileName) {
 
     // 파일 유효성 검사
     private String getFileExtension(String fileName) {
-        if (fileName.length() == 0) {
+        if (fileName == null || fileName.isEmpty()) {
             throw new NotFoundException(ErrorStatus.NOT_FOUND_IMAGE_EXCEPTION, ErrorStatus.NOT_FOUND_IMAGE_EXCEPTION.getMessage());
         }
+        int dotIndex = fileName.lastIndexOf(".");
+        // 파일명에 "."가 아예 없으면(lastIndexOf가 -1) substring(-1)에서 그대로
+        // StringIndexOutOfBoundsException(500)이 나던 부분 — 확장자 없는 파일로 명확히 처리한다.
+        if (dotIndex == -1) {
+            throw new BadRequestException(ErrorStatus.NOT_FOUND_IMAGE_EXCEPTION, ErrorStatus.NOT_FOUND_IMAGE_EXCEPTION.getMessage());
+        }
         ArrayList<String> fileValidate = new ArrayList<>();
         fileValidate.add(".jpg");
         fileValidate.add(".jpeg");
         fileValidate.add(".png");
         fileValidate.add(".JPG");
         fileValidate.add(".JPEG");
         fileValidate.add(".PNG");
-        String idxFileName = fileName.substring(fileName.lastIndexOf("."));
+        String idxFileName = fileName.substring(dotIndex);
         if (!fileValidate.contains(idxFileName)) {
             throw new BadRequestException(ErrorStatus.NOT_FOUND_IMAGE_EXCEPTION, ErrorStatus.NOT_FOUND_IMAGE_EXCEPTION.getMessage());
         }
-        return fileName.substring(fileName.lastIndexOf("."));
+        return idxFileName;
     }
 
     // 이미지 삭제

src/test/java/org/runnect/server/banner/service/BannerServiceTest.java

@@ -0,0 +1,58 @@
+package org.runnect.server.banner.service;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
+
+import java.util.Arrays;
+import java.util.Collections;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.runnect.server.banner.dto.response.GetBannerResponseDto;
+import org.runnect.server.banner.entity.Banner;
+import org.runnect.server.banner.repository.BannerRepository;
+import org.springframework.test.util.ReflectionTestUtils;
+
+@ExtendWith(MockitoExtension.class)
+class BannerServiceTest {
+
+    @Mock
+    private BannerRepository bannerRepository;
+
+    private BannerService bannerService;
+
+    private Banner buildBanner(Long id, String imageUrl, String linkUrl, int sortOrder) {
+        Banner banner = Banner.builder().imageUrl(imageUrl).linkUrl(linkUrl).sortOrder(sortOrder).build();
+        ReflectionTestUtils.setField(banner, "id", id);
+        return banner;
+    }
+
+    @Test
+    void 활성_배너를_정렬된_순서_그대로_0부터_인덱싱해서_반환한다() {
+        bannerService = new BannerService(bannerRepository);
+        Banner first = buildBanner(1L, "image1.png", "https://a.com", 0);
+        Banner second = buildBanner(2L, "image2.png", "https://b.com", 1);
+        when(bannerRepository.findByIsActiveTrueOrderBySortOrderAscIdAsc())
+            .thenReturn(Arrays.asList(first, second));
+
+        GetBannerResponseDto response = bannerService.getBanners();
+
+        assertThat(response.getBanners()).hasSize(2);
+        assertThat(response.getBanners().get(0).getIndex()).isEqualTo(0);
+        assertThat(response.getBanners().get(0).getImageUrl()).isEqualTo("image1.png");
+        assertThat(response.getBanners().get(1).getIndex()).isEqualTo(1);
+        assertThat(response.getBanners().get(1).getLinkUrl()).isEqualTo("https://b.com");
+    }
+
+    @Test
+    void 활성_배너가_없으면_빈_목록을_반환한다() {
+        bannerService = new BannerService(bannerRepository);
+        when(bannerRepository.findByIsActiveTrueOrderBySortOrderAscIdAsc())
+            .thenReturn(Collections.emptyList());
+
+        GetBannerResponseDto response = bannerService.getBanners();
+
+        assertThat(response.getBanners()).isEmpty();
+    }
+}

src/test/java/org/runnect/server/external/aws/S3ServiceTest.java

@@ -0,0 +1,120 @@
+package org.runnect.server.external.aws;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import com.amazonaws.services.s3.AmazonS3;
+import com.amazonaws.services.s3.model.PutObjectRequest;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.runnect.server.common.exception.BadRequestException;
+import org.runnect.server.common.exception.NotFoundException;
+import org.springframework.mock.web.MockMultipartFile;
+import org.springframework.test.util.ReflectionTestUtils;
+import org.springframework.web.multipart.MultipartFile;
+
+@ExtendWith(MockitoExtension.class)
+class S3ServiceTest {
+
+    @Mock
+    private AmazonS3 amazonS3;
+
+    private S3Service s3Service;
+
+    @BeforeEach
+    void setUp() {
+        s3Service = new S3Service(amazonS3);
+        ReflectionTestUtils.setField(s3Service, "bucket", "runnect-test-bucket");
+    }
+
+    private void stubUploadedUrl() throws Exception {
+        when(amazonS3.getUrl(any(), any())).thenReturn(
+            new URL("https://runnect-test-bucket.s3.ap-northeast-2.amazonaws.com/course/image/test.jpg"));
+    }
+
+    @Nested
+    @DisplayName("uploadImage")
+    class UploadImage {
+
+        @Test
+        @DisplayName("정상적인 이미지 파일이면 업로드하고 URL을 반환한다")
+        void 정상_업로드() throws Exception {
+            stubUploadedUrl();
+            MultipartFile file = new MockMultipartFile("image", "photo.jpg", "image/jpeg", "content".getBytes());
+
+            String url = s3Service.uploadImage(file, "course");
+
+            assertThat(url).isEqualTo(
+                "https://runnect-test-bucket.s3.ap-northeast-2.amazonaws.com/course/image/test.jpg");
+        }
+
+        @Test
+        @DisplayName("대문자 확장자(.PNG)도 정상 업로드된다")
+        void 대문자_확장자() throws Exception {
+            stubUploadedUrl();
+            MultipartFile file = new MockMultipartFile("image", "photo.PNG", "image/png", "content".getBytes());
+
+            assertThat(s3Service.uploadImage(file, "course")).isNotNull();
+        }
+
+        @Test
+        @DisplayName("지원하지 않는 확장자면 BadRequestException")
+        void 지원하지_않는_확장자() {
+            MultipartFile file = new MockMultipartFile("image", "photo.gif", "image/gif", "content".getBytes());
+
+            assertThatThrownBy(() -> s3Service.uploadImage(file, "course"))
+                .isInstanceOf(BadRequestException.class);
+        }
+
+        @Test
+        @DisplayName("[버그 수정 검증] 파일명이 null이면 500(NPE) 대신 NotFoundException")
+        void 파일명이_null() {
+            MultipartFile file = new MockMultipartFile("image", null, "image/jpeg", "content".getBytes());
+
+            assertThatThrownBy(() -> s3Service.uploadImage(file, "course"))
+                .isInstanceOf(NotFoundException.class);
+        }
+
+        @Test
+        @DisplayName("파일명이 빈 문자열이면 NotFoundException")
+        void 파일명이_빈문자열() {
+            MultipartFile file = new MockMultipartFile("image", "", "image/jpeg", "content".getBytes());
+
+            assertThatThrownBy(() -> s3Service.uploadImage(file, "course"))
+                .isInstanceOf(NotFoundException.class);
+        }
+
+        @Test
+        @DisplayName("[버그 수정 검증] 확장자(.)가 없는 파일명이면 500(StringIndexOutOfBoundsException) 대신 BadRequestException")
+        void 확장자가_없는_파일명() {
+            MultipartFile file = new MockMultipartFile("image", "photo_without_extension", "image/jpeg",
+                "content".getBytes());
+
+            assertThatThrownBy(() -> s3Service.uploadImage(file, "course"))
+                .isInstanceOf(BadRequestException.class);
+        }
+
+        @Test
+        @DisplayName("파일 스트림을 읽는 중 오류가 나면 NotFoundException")
+        void 스트림_읽기_실패() throws IOException {
+            MultipartFile file = mock(MultipartFile.class);
+            when(file.getOriginalFilename()).thenReturn("photo.jpg");
+            when(file.getInputStream()).thenThrow(new IOException("disk error"));
+
+            assertThatThrownBy(() -> s3Service.uploadImage(file, "course"))
+                .isInstanceOf(NotFoundException.class);
+        }
+    }
+}