카드 매입 승인 경로 Spring Boot 3 전환 (ACX-E2E-1785394564819)

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>3.2.5</version>
+        <relativePath/>
+    </parent>
+
+    <groupId>com.acquirex</groupId>
+    <artifactId>card-acquisition</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <name>card-acquisition</name>
+    <description>카드 매입 승인 경로 - Spring Boot 3 전환</description>
+
+    <properties>
+        <java.version>17</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-validation</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>

src/main/java/com/acquirex/cardacquisition/CardAcquisitionApplication.java

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+package com.acquirex.cardacquisition;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class CardAcquisitionApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(CardAcquisitionApplication.class, args);
+    }
+}

src/main/java/com/acquirex/cardacquisition/controller/CardAcquisitionController.java

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+package com.acquirex.cardacquisition.controller;
+
+import com.acquirex.cardacquisition.dto.AcquisitionRequest;
+import com.acquirex.cardacquisition.dto.AcquisitionResponse;
+import com.acquirex.cardacquisition.service.CardAcquisitionService;
+import jakarta.validation.Valid;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+/** Spring Boot 3 전환: javax.servlet → jakarta.servlet */
+@RestController
+@RequestMapping("/api/v1/acquisitions")
+public class CardAcquisitionController {
+
+    private final CardAcquisitionService service;
+
+    public CardAcquisitionController(CardAcquisitionService service) {
+        this.service = service;
+    }
+
+    @PostMapping
+    public ResponseEntity<AcquisitionResponse> requestAcquisition(@Valid @RequestBody AcquisitionRequest request) {
+        return ResponseEntity.status(HttpStatus.CREATED).body(service.requestAcquisition(request));
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<AcquisitionResponse> getAcquisition(@PathVariable Long id) {
+        return ResponseEntity.ok(service.getAcquisition(id));
+    }
+
+    @GetMapping("/merchant/{merchantId}")
+    public ResponseEntity<List<AcquisitionResponse>> getAcquisitionsByMerchant(@PathVariable String merchantId) {
+        return ResponseEntity.ok(service.getAcquisitionsByMerchant(merchantId));
+    }
+
+    @GetMapping("/pending")
+    public ResponseEntity<List<AcquisitionResponse>> getPendingAcquisitions() {
+        return ResponseEntity.ok(service.getPendingAcquisitions());
+    }
+
+    @PostMapping("/{id}/cancel")
+    public ResponseEntity<AcquisitionResponse> cancelAcquisition(@PathVariable Long id) {
+        return ResponseEntity.ok(service.cancelAcquisition(id));
+    }
+}
+
+/** Spring Boot 3 전환: javax.validation → jakarta.validation */
+@RestControllerAdvice
+class GlobalExceptionHandler {
+
+    @ExceptionHandler(CardAcquisitionService.AcquisitionNotFoundException.class)
+    public ResponseEntity<java.util.Map<String, Object>> handleNotFound(CardAcquisitionService.AcquisitionNotFoundException ex) {
+        return buildErrorResponse(HttpStatus.NOT_FOUND, ex.getMessage());
+    }
+
+    @ExceptionHandler(CardAcquisitionService.InvalidAcquisitionException.class)
+    public ResponseEntity<java.util.Map<String, Object>> handleInvalid(CardAcquisitionService.InvalidAcquisitionException ex) {
+        return buildErrorResponse(HttpStatus.BAD_REQUEST, ex.getMessage());
+    }
+
+    @ExceptionHandler(IllegalStateException.class)
+    public ResponseEntity<java.util.Map<String, Object>> handleIllegalState(IllegalStateException ex) {
+        return buildErrorResponse(HttpStatus.CONFLICT, ex.getMessage());
+    }
+
+    @ExceptionHandler(org.springframework.web.bind.MethodArgumentNotValidException.class)
+    public ResponseEntity<java.util.Map<String, Object>> handleValidationErrors(
+            org.springframework.web.bind.MethodArgumentNotValidException ex) {
+        java.util.Map<String, String> fieldErrors = new java.util.HashMap<>();
+        ex.getBindingResult().getFieldErrors().forEach(e -> fieldErrors.put(e.getField(), e.getDefaultMessage()));
+
+        java.util.Map<String, Object> body = new java.util.HashMap<>();
+        body.put("timestamp", LocalDateTime.now());
+        body.put("status", HttpStatus.BAD_REQUEST.value());
+        body.put("error", "Validation Failed");
+        body.put("fieldErrors", fieldErrors);
+        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(body);
+    }
+
+    private ResponseEntity<java.util.Map<String, Object>> buildErrorResponse(HttpStatus status, String message) {
+        java.util.Map<String, Object> body = new java.util.HashMap<>();
+        body.put("timestamp", LocalDateTime.now());
+        body.put("status", status.value());
+        body.put("error", status.getReasonPhrase());
+        body.put("message", message);
+        return ResponseEntity.status(status).body(body);
+    }
+}

src/main/java/com/acquirex/cardacquisition/entity/CardAcquisition.java

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+package com.acquirex.cardacquisition.entity;
+
+import jakarta.persistence.*;
+import jakarta.validation.constraints.*;
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+
+/** Spring Boot 3 전환: javax.persistence → jakarta.persistence */
+@Entity
+@Table(name = "card_acquisitions")
+public class CardAcquisition {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "merchant_id", nullable = false)
+    private String merchantId;
+
+    @Column(name = "card_number", nullable = false)
+    private String cardNumber;
+
+    @Column(name = "amount", nullable = false, precision = 15, scale = 2)
+    private BigDecimal amount;
+
+    @Column(name = "currency", nullable = false, length = 3)
+    private String currency;
+
+    @Enumerated(EnumType.STRING)
+    @Column(name = "status", nullable = false)
+    private AcquisitionStatus status = AcquisitionStatus.PENDING;
+
+    @Column(name = "approval_code")
+    private String approvalCode;
+
+    @Column(name = "request_time", nullable = false)
+    private LocalDateTime requestTime = LocalDateTime.now();
+
+    @Column(name = "approval_time")
+    private LocalDateTime approvalTime;
+
+    @Column(name = "reject_reason")
+    private String rejectReason;
+
+    public CardAcquisition() {}
+
+    public CardAcquisition(String merchantId, String cardNumber, BigDecimal amount, String currency) {
+        this.merchantId = merchantId;
+        this.cardNumber = cardNumber;
+        this.amount = amount;
+        this.currency = currency;
+        this.status = AcquisitionStatus.PENDING;
+        this.requestTime = LocalDateTime.now();
+    }
+
+    public Long getId() { return id; }
+    public void setId(Long id) { this.id = id; }
+    public String getMerchantId() { return merchantId; }
+    public void setMerchantId(String merchantId) { this.merchantId = merchantId; }
+    public String getCardNumber() { return cardNumber; }
+    public void setCardNumber(String cardNumber) { this.cardNumber = cardNumber; }
+    public BigDecimal getAmount() { return amount; }
+    public void setAmount(BigDecimal amount) { this.amount = amount; }
+    public String getCurrency() { return currency; }
+    public void setCurrency(String currency) { this.currency = currency; }
+    public AcquisitionStatus getStatus() { return status; }
+    public void setStatus(AcquisitionStatus status) { this.status = status; }
+    public String getApprovalCode() { return approvalCode; }
+    public void setApprovalCode(String approvalCode) { this.approvalCode = approvalCode; }
+    public LocalDateTime getRequestTime() { return requestTime; }
+    public void setRequestTime(LocalDateTime requestTime) { this.requestTime = requestTime; }
+    public LocalDateTime getApprovalTime() { return approvalTime; }
+    public void setApprovalTime(LocalDateTime approvalTime) { this.approvalTime = approvalTime; }
+    public String getRejectReason() { return rejectReason; }
+    public void setRejectReason(String rejectReason) { this.rejectReason = rejectReason; }
+
+    public void approve(String approvalCode) {
+        this.status = AcquisitionStatus.APPROVED;
+        this.approvalCode = approvalCode;
+        this.approvalTime = LocalDateTime.now();
+    }
+
+    public void reject(String reason) {
+        this.status = AcquisitionStatus.REJECTED;
+        this.rejectReason = reason;
+        this.approvalTime = LocalDateTime.now();
+    }
+
+    /** Spring Boot 3 전환: javax.persistence → jakarta.persistence */
+    public enum AcquisitionStatus {
+        PENDING, APPROVED, REJECTED, CANCELLED
+    }
+}
+
+/** Spring Boot 3 전환: javax.validation → jakarta.validation */
+class AcquisitionRequest {
+    @NotBlank(message = "상점 ID는 필수입니다")
+    private String merchantId;
+
+    @NotBlank(message = "카드번호는 필수입니다")
+    @Pattern(regexp = "\\d{10,19}", message = "유효하지 않은 카드번호 형식입니다")
+    private String cardNumber;
+
+    @NotNull(message = "금액은 필수입니다")
+    @DecimalMin(value = "0.01", message = "금액은 0보다 커야 합니다")
+    private BigDecimal amount;
+
+    @NotBlank(message = "통화는 필수입니다")
+    @Size(min = 3, max = 3, message = "통화 코드는 3자리입니다")
+    private String currency;
+
+    public AcquisitionRequest() {}
+    public AcquisitionRequest(String merchantId, String cardNumber, BigDecimal amount, String currency) {
+        this.merchantId = merchantId;
+        this.cardNumber = cardNumber;
+        this.amount = amount;
+        this.currency = currency;
+    }
+
+    public String getMerchantId() { return merchantId; }
+    public void setMerchantId(String merchantId) { this.merchantId = merchantId; }
+    public String getCardNumber() { return cardNumber; }
+    public void setCardNumber(String cardNumber) { this.cardNumber = cardNumber; }
+    public BigDecimal getAmount() { return amount; }
+    public void setAmount(BigDecimal amount) { this.amount = amount; }
+    public String getCurrency() { return currency; }
+    public void setCurrency(String currency) { this.currency = currency; }
+}
+
+class AcquisitionResponse {
+    private Long id;
+    private String merchantId;
+    private String maskedCardNumber;
+    private BigDecimal amount;
+    private String currency;
+    private CardAcquisition.AcquisitionStatus status;
+    private String approvalCode;
+    private LocalDateTime requestTime;
+    private LocalDateTime approvalTime;
+    private String message;
+
+    public AcquisitionResponse() {}
+
+    public static AcquisitionResponse fromEntity(CardAcquisition entity) {
+        AcquisitionResponse response = new AcquisitionResponse();
+        response.setId(entity.getId());
+        response.setMerchantId(entity.getMerchantId());
+        response.setMaskedCardNumber(maskCardNumber(entity.getCardNumber()));
+        response.setAmount(entity.getAmount());
+        response.setCurrency(entity.getCurrency());
+        response.setStatus(entity.getStatus());
+        response.setApprovalCode(entity.getApprovalCode());
+        response.setRequestTime(entity.getRequestTime());
+        response.setApprovalTime(entity.getApprovalTime());
+        return response;
+    }
+
+    private static String maskCardNumber(String cardNumber) {
+        if (cardNumber == null || cardNumber.length() < 8) return "****";
+        return cardNumber.substring(0, 4) + "****" + cardNumber.substring(cardNumber.length() - 4);
+    }
+
+    public Long getId() { return id; }
+    public void setId(Long id) { this.id = id; }
+    public String getMerchantId() { return merchantId; }
+    public void setMerchantId(String merchantId) { this.merchantId = merchantId; }
+    public String getMaskedCardNumber() { return maskedCardNumber; }
+    public void setMaskedCardNumber(String maskedCardNumber) { this.maskedCardNumber = maskedCardNumber; }
+    public BigDecimal getAmount() { return amount; }
+    public void setAmount(BigDecimal amount) { this.amount = amount; }
+    public String getCurrency() { return currency; }
+    public void setCurrency(String currency) { this.currency = currency; }
+    public CardAcquisition.AcquisitionStatus getStatus() { return status; }
+    public void setStatus(CardAcquisition.AcquisitionStatus status) { this.status = status; }
+    public String getApprovalCode() { return approvalCode; }
+    public void setApprovalCode(String approvalCode) { this.approvalCode = approvalCode; }
+    public LocalDateTime getRequestTime() { return requestTime; }
+    public void setRequestTime(LocalDateTime requestTime) { this.requestTime = requestTime; }
+    public LocalDateTime getApprovalTime() { return approvalTime; }
+    public void setApprovalTime(LocalDateTime approvalTime) { this.approvalTime = approvalTime; }
+    public String getMessage() { return message; }
+    public void setMessage(String message) { this.message = message; }
+}

src/main/java/com/acquirex/cardacquisition/repository/CardAcquisitionRepository.java

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+package com.acquirex.cardacquisition.repository;
+
+import com.acquirex.cardacquisition.entity.CardAcquisition;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.Optional;
+
+@Repository
+public interface CardAcquisitionRepository extends JpaRepository<CardAcquisition, Long> {
+
+    List<CardAcquisition> findByMerchantId(String merchantId);
+
+    List<CardAcquisition> findByStatus(CardAcquisition.AcquisitionStatus status);
+
+    Optional<CardAcquisition> findByApprovalCode(String approvalCode);
+
+    List<CardAcquisition> findByRequestTimeBetween(LocalDateTime start, LocalDateTime end);
+
+    List<CardAcquisition> findByMerchantIdAndStatus(String merchantId, CardAcquisition.AcquisitionStatus status);
+}

src/main/java/com/acquirex/cardacquisition/service/CardAcquisitionService.java

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+package com.acquirex.cardacquisition.service;
+
+import com.acquirex.cardacquisition.entity.CardAcquisition;
+import com.acquirex.cardacquisition.repository.CardAcquisitionRepository;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.UUID;
+import java.util.stream.Collectors;
+
+@Service
+public class CardAcquisitionService {
+
+    private static final BigDecimal MAX_SINGLE_TRANSACTION = new BigDecimal("10000000");
+    private static final BigDecimal DAILY_LIMIT = new BigDecimal("50000000");
+
+    private final CardAcquisitionRepository repository;
+
+    public CardAcquisitionService(CardAcquisitionRepository repository) {
+        this.repository = repository;
+    }
+
+    @Transactional
+    public AcquisitionResponse requestAcquisition(AcquisitionRequest request) {
+        validateRequest(request);
+
+        CardAcquisition acquisition = new CardAcquisition(
+                request.getMerchantId(), request.getCardNumber(), request.getAmount(), request.getCurrency());
+
+        CardAcquisition saved = repository.save(acquisition);
+        String approvalCode = generateApprovalCode();
+        saved.approve(approvalCode);
+
+        AcquisitionResponse response = AcquisitionResponse.fromEntity(repository.save(saved));
+        response.setMessage("매입 승인이 완료되었습니다");
+        return response;
+    }
+
+    @Transactional(readOnly = true)
+    public AcquisitionResponse getAcquisition(Long id) {
+        CardAcquisition acquisition = repository.findById(id)
+                .orElseThrow(() -> new AcquisitionNotFoundException("매입 정보를 찾을 수 없습니다: " + id));
+        AcquisitionResponse response = AcquisitionResponse.fromEntity(acquisition);
+        response.setMessage("매입 정보를 조회했습니다");
+        return response;
+    }
+
+    @Transactional(readOnly = true)
+    public List<AcquisitionResponse> getAcquisitionsByMerchant(String merchantId) {
+        return repository.findByMerchantId(merchantId).stream()
+                .map(AcquisitionResponse::fromEntity).collect(Collectors.toList());
+    }
+
+    @Transactional(readOnly = true)
+    public List<AcquisitionResponse> getPendingAcquisitions() {
+        return repository.findByStatus(CardAcquisition.AcquisitionStatus.PENDING).stream()
+                .map(AcquisitionResponse::fromEntity).collect(Collectors.toList());
+    }
+
+    @Transactional
+    public AcquisitionResponse cancelAcquisition(Long id) {
+        CardAcquisition acquisition = repository.findById(id)
+                .orElseThrow(() -> new AcquisitionNotFoundException("매입 정보를 찾을 수 없습니다: " + id));
+
+        if (acquisition.getStatus() == CardAcquisition.AcquisitionStatus.CANCELLED) {
+            throw new IllegalStateException("이미 취소된 매입입니다");
+        }
+
+        acquisition.setStatus(CardAcquisition.AcquisitionStatus.CANCELLED);
+        acquisition.setApprovalTime(LocalDateTime.now());
+
+        AcquisitionResponse response = AcquisitionResponse.fromEntity(repository.save(acquisition));
+        response.setMessage("매입이 취소되었습니다");
+        return response;
+    }
+
+    private void validateRequest(AcquisitionRequest request) {
+        if (request.getAmount().compareTo(MAX_SINGLE_TRANSACTION) > 0) {
+            throw new InvalidAcquisitionException("단일 거래 한도를 초과했습니다");
+        }
+
+        LocalDateTime startOfDay = LocalDateTime.now().toLocalDate().atStartOfDay();
+        BigDecimal todayTotal = repository.findByRequestTimeBetween(startOfDay, startOfDay.plusDays(1)).stream()
+                .filter(a -> a.getMerchantId().equals(request.getMerchantId()))
+                .map(CardAcquisition::getAmount).reduce(BigDecimal.ZERO, BigDecimal::add);
+
+        if (todayTotal.add(request.getAmount()).compareTo(DAILY_LIMIT) > 0) {
+            throw new InvalidAcquisitionException("일일 한도를 초과했습니다");
+        }
+    }
+
+    private String generateApprovalCode() {
+        return "APR" + UUID.randomUUID().toString().substring(0, 12).toUpperCase();
+    }
+
+    public static class AcquisitionNotFoundException extends RuntimeException {
+        public AcquisitionNotFoundException(String message) { super(message); }
+    }
+
+    public static class InvalidAcquisitionException extends RuntimeException {
+        public InvalidAcquisitionException(String message) { super(message); }
+    }
+}

src/main/resources/application.properties

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+spring.application.name=card-acquisition
+
+# H2 Database
+spring.datasource.url=jdbc:h2:mem:cardacquisition;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
+spring.datasource.driverClassName=org.h2.Driver
+spring.datasource.username=sa
+spring.datasource.password=
+
+# JPA/Hibernate 6 (Spring Boot 3)
+spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
+spring.jpa.hibernate.ddl-auto=create-drop
+spring.jpa.show-sql=true
+spring.jpa.properties.hibernate.format_sql=true
+
+# H2 Console
+spring.h2.console.enabled=true
+spring.h2.console.path=/h2-console
+
+# Server
+server.port=8080
+
+# Jackson
+spring.jackson.serialization.write-dates-as-timestamps=false
+spring.jackson.date-format=yyyy-MM-dd'T'HH:mm:ss

src/test/java/com/acquirex/cardacquisition/CardAcquisitionServiceTest.java

@@ -0,0 +1,98 @@
+package com.acquirex.cardacquisition;
+
+import com.acquirex.cardacquisition.entity.CardAcquisition;
+import com.acquirex.cardacquisition.repository.CardAcquisitionRepository;
+import com.acquirex.cardacquisition.service.CardAcquisitionService;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+@ExtendWith(MockitoExtension.class)
+class CardAcquisitionServiceTest {
+
+    @Mock
+    private CardAcquisitionRepository repository;
+
+    private CardAcquisitionService service;
+
+    @BeforeEach
+    void setUp() {
+        service = new CardAcquisitionService(repository);
+    }
+
+    @Test
+    void requestAcquisition_ValidRequest_ReturnsApprovedResponse() {
+        when(repository.save(any(CardAcquisition.class))).thenAnswer(i -> {
+            CardAcquisition e = i.getArgument(0);
+            if (e.getId() == null) e.setId(1L);
+            return e;
+        });
+        when(repository.findByRequestTimeBetween(any(), any())).thenReturn(List.of());
+
+        AcquisitionRequest request = new AcquisitionRequest("MERCHANT001", "1234567890123456", new BigDecimal("50000"), "KRW");
+        AcquisitionResponse response = service.requestAcquisition(request);
+
+        assertNotNull(response);
+        assertEquals(1L, response.getId());
+        assertEquals(CardAcquisition.AcquisitionStatus.APPROVED, response.getStatus());
+        assertTrue(response.getApprovalCode().startsWith("APR"));
+        verify(repository, times(2)).save(any(CardAcquisition.class));
+    }
+
+    @Test
+    void requestAcquisition_ExceedsLimit_ThrowsException() {
+        AcquisitionRequest request = new AcquisitionRequest("MERCHANT001", "1234567890123456", new BigDecimal("15000000"), "KRW");
+        assertThrows(CardAcquisitionService.InvalidAcquisitionException.class, () -> service.requestAcquisition(request));
+    }
+
+    @Test
+    void getAcquisition_ExistingId_ReturnsResponse() {
+        CardAcquisition entity = new CardAcquisition("M1", "1111", new BigDecimal("1000"), "KRW");
+        entity.setId(1L);
+        entity.approve("APR123");
+        when(repository.findById(1L)).thenReturn(Optional.of(entity));
+
+        AcquisitionResponse response = service.getAcquisition(1L);
+
+        assertNotNull(response);
+        assertEquals(CardAcquisition.AcquisitionStatus.APPROVED, response.getStatus());
+    }
+
+    @Test
+    void getAcquisition_NotFound_ThrowsException() {
+        when(repository.findById(999L)).thenReturn(Optional.empty());
+        assertThrows(CardAcquisitionService.AcquisitionNotFoundException.class, () -> service.getAcquisition(999L));
+    }
+
+    @Test
+    void cancelAcquisition_ExistingPending_ReturnsCancelled() {
+        CardAcquisition entity = new CardAcquisition("M1", "1111", new BigDecimal("1000"), "KRW");
+        entity.setId(1L);
+        when(repository.findById(1L)).thenReturn(Optional.of(entity));
+        when(repository.save(any())).thenAnswer(i -> i.getArgument(0));
+
+        AcquisitionResponse response = service.cancelAcquisition(1L);
+
+        assertEquals(CardAcquisition.AcquisitionStatus.CANCELLED, response.getStatus());
+    }
+
+    @Test
+    void cancelAcquisition_AlreadyCancelled_ThrowsException() {
+        CardAcquisition entity = new CardAcquisition("M1", "1111", new BigDecimal("1000"), "KRW");
+        entity.setId(1L);
+        entity.setStatus(CardAcquisition.AcquisitionStatus.CANCELLED);
+        when(repository.findById(1L)).thenReturn(Optional.of(entity));
+
+        assertThrows(IllegalStateException.class, () -> service.cancelAcquisition(1L));
+    }
+}