unit-test-mapper-converter by giuseppe-trisciuoglio/developer-kit
npx skills add https://github.com/giuseppe-trisciuoglio/developer-kit --skill unit-test-mapper-converter本技能提供了单元测试 MapStruct 映射器和自定义转换器类的模式。它涵盖了测试字段映射准确性、空值处理、类型转换、嵌套对象转换、双向映射、枚举映射和部分更新,以实现全面的映射测试覆盖。
在以下情况下使用此技能:
@Mapping 注解是否正确工作@ValueMapping 是否正确转换枚举值@MappingTarget 仅更新指定的字段广告位招租
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<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct</artifactId>
<version>1.5.5.Final</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<scope>test</scope>
</dependency>
dependencies {
implementation("org.mapstruct:mapstruct:1.5.5.Final")
testImplementation("org.junit.jupiter:junit-jupiter")
testImplementation("org.assertj:assertj-core")
}
// Mapper interface
@Mapper(componentModel = "spring")
public interface UserMapper {
UserDto toDto(User user);
User toEntity(UserDto dto);
List<UserDto> toDtos(List<User> users);
}
// Unit test
import org.junit.jupiter.api.Test;
import static org.assertj.core.api.Assertions.*;
class UserMapperTest {
private final UserMapper userMapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMapUserToDto() {
User user = new User(1L, "Alice", "alice@example.com", 25);
UserDto dto = userMapper.toDto(user);
assertThat(dto)
.isNotNull()
.extracting("id", "name", "email", "age")
.containsExactly(1L, "Alice", "alice@example.com", 25);
}
@Test
void shouldMapDtoToEntity() {
UserDto dto = new UserDto(1L, "Alice", "alice@example.com", 25);
User user = userMapper.toEntity(dto);
assertThat(user)
.isNotNull()
.hasFieldOrPropertyWithValue("id", 1L)
.hasFieldOrPropertyWithValue("name", "Alice");
}
@Test
void shouldMapListOfUsers() {
List<User> users = List.of(
new User(1L, "Alice", "alice@example.com", 25),
new User(2L, "Bob", "bob@example.com", 30)
);
List<UserDto> dtos = userMapper.toDtos(users);
assertThat(dtos)
.hasSize(2)
.extracting(UserDto::getName)
.containsExactly("Alice", "Bob");
}
@Test
void shouldHandleNullEntity() {
UserDto dto = userMapper.toDto(null);
assertThat(dto).isNull();
}
}
// Entities with nesting
class User {
private Long id;
private String name;
private Address address;
private List<Phone> phones;
}
// Mapper with nested mapping
@Mapper(componentModel = "spring")
public interface UserMapper {
UserDto toDto(User user);
User toEntity(UserDto dto);
}
// Unit test for nested objects
class NestedObjectMapperTest {
private final UserMapper userMapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMapNestedAddress() {
Address address = new Address("123 Main St", "New York", "NY", "10001");
User user = new User(1L, "Alice", address);
UserDto dto = userMapper.toDto(user);
assertThat(dto.getAddress())
.isNotNull()
.hasFieldOrPropertyWithValue("street", "123 Main St")
.hasFieldOrPropertyWithValue("city", "New York");
}
@Test
void shouldMapListOfNestedPhones() {
List<Phone> phones = List.of(
new Phone("123-456-7890", "MOBILE"),
new Phone("987-654-3210", "HOME")
);
User user = new User(1L, "Alice", null, phones);
UserDto dto = userMapper.toDto(user);
assertThat(dto.getPhones())
.hasSize(2)
.extracting(PhoneDto::getNumber)
.containsExactly("123-456-7890", "987-654-3210");
}
@Test
void shouldHandleNullNestedObjects() {
User user = new User(1L, "Alice", null);
UserDto dto = userMapper.toDto(user);
assertThat(dto.getAddress()).isNull();
}
}
@Mapping 注解的映射器@Mapper(componentModel = "spring")
public interface ProductMapper {
@Mapping(source = "name", target = "productName")
@Mapping(source = "price", target = "salePrice")
@Mapping(target = "discount", expression = "java(product.getPrice() * 0.1)")
ProductDto toDto(Product product);
@Mapping(source = "productName", target = "name")
@Mapping(source = "salePrice", target = "price")
Product toEntity(ProductDto dto);
}
class CustomMappingTest {
private final ProductMapper mapper = Mappers.getMapper(ProductMapper.class);
@Test
void shouldMapFieldsWithCustomNames() {
Product product = new Product(1L, "Laptop", 999.99);
ProductDto dto = mapper.toDto(product);
assertThat(dto)
.hasFieldOrPropertyWithValue("productName", "Laptop")
.hasFieldOrPropertyWithValue("salePrice", 999.99);
}
@Test
void shouldCalculateDiscountFromExpression() {
Product product = new Product(1L, "Laptop", 100.0);
ProductDto dto = mapper.toDto(product);
assertThat(dto.getDiscount()).isEqualTo(10.0);
}
@Test
void shouldReverseMapCustomFields() {
ProductDto dto = new ProductDto(1L, "Laptop", 999.99);
Product product = mapper.toEntity(dto);
assertThat(product)
.hasFieldOrPropertyWithValue("name", "Laptop")
.hasFieldOrPropertyWithValue("price", 999.99);
}
}
// Enum with different representation
enum UserStatus { ACTIVE, INACTIVE, SUSPENDED }
enum UserStatusDto { ENABLED, DISABLED, LOCKED }
@Mapper(componentModel = "spring")
public interface UserMapper {
@ValueMapping(source = "ACTIVE", target = "ENABLED")
@ValueMapping(source = "INACTIVE", target = "DISABLED")
@ValueMapping(source = "SUSPENDED", target = "LOCKED")
UserStatusDto toStatusDto(UserStatus status);
}
class EnumMapperTest {
private final UserMapper mapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMapActiveToEnabled() {
UserStatusDto dto = mapper.toStatusDto(UserStatus.ACTIVE);
assertThat(dto).isEqualTo(UserStatusDto.ENABLED);
}
@Test
void shouldMapSuspendedToLocked() {
UserStatusDto dto = mapper.toStatusDto(UserStatus.SUSPENDED);
assertThat(dto).isEqualTo(UserStatusDto.LOCKED);
}
}
// Custom converter class
public class DateFormatter {
private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
public static String format(LocalDate date) {
return date != null ? date.format(formatter) : null;
}
public static LocalDate parse(String dateString) {
return dateString != null ? LocalDate.parse(dateString, formatter) : null;
}
}
// Unit test
class DateFormatterTest {
@Test
void shouldFormatLocalDateToString() {
LocalDate date = LocalDate.of(2024, 1, 15);
String result = DateFormatter.format(date);
assertThat(result).isEqualTo("2024-01-15");
}
@Test
void shouldParseStringToLocalDate() {
String dateString = "2024-01-15";
LocalDate result = DateFormatter.parse(dateString);
assertThat(result).isEqualTo(LocalDate.of(2024, 1, 15));
}
@Test
void shouldHandleNullInFormat() {
String result = DateFormatter.format(null);
assertThat(result).isNull();
}
@Test
void shouldHandleInvalidDateFormat() {
assertThatThrownBy(() -> DateFormatter.parse("invalid-date"))
.isInstanceOf(DateTimeParseException.class);
}
}
class BidirectionalMapperTest {
private final UserMapper mapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMaintainDataInRoundTrip() {
User original = new User(1L, "Alice", "alice@example.com", 25);
UserDto dto = mapper.toDto(original);
User restored = mapper.toEntity(dto);
assertThat(restored)
.hasFieldOrPropertyWithValue("id", original.getId())
.hasFieldOrPropertyWithValue("name", original.getName())
.hasFieldOrPropertyWithValue("email", original.getEmail())
.hasFieldOrPropertyWithValue("age", original.getAge());
}
@Test
void shouldPreserveAllFieldsInBothDirections() {
Address address = new Address("123 Main", "NYC", "NY", "10001");
User user = new User(1L, "Alice", "alice@example.com", 25, address);
UserDto dto = mapper.toDto(user);
User restored = mapper.toEntity(dto);
assertThat(restored).usingRecursiveComparison().isEqualTo(user);
}
}
@Mapper(componentModel = "spring")
public interface UserMapper {
void updateEntity(@MappingTarget User entity, UserDto dto);
}
class PartialMapperTest {
private final UserMapper mapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldUpdateExistingEntity() {
User existing = new User(1L, "Alice", "alice@old.com", 25);
UserDto dto = new UserDto(1L, "Alice", "alice@new.com", 26);
mapper.updateEntity(existing, dto);
assertThat(existing)
.hasFieldOrPropertyWithValue("email", "alice@new.com")
.hasFieldOrPropertyWithValue("age", 26);
}
@Test
void shouldNotUpdateFieldsNotInDto() {
User existing = new User(1L, "Alice", "alice@example.com", 25);
UserDto dto = new UserDto(1L, "Bob", null, 0);
mapper.updateEntity(existing, dto);
// Assuming null-aware mapping is configured
assertThat(existing.getEmail()).isEqualTo("alice@example.com");
}
}
@Component 进行依赖注入@Mapping 中的表达式在编译时不会验证映射期间出现空指针异常:检查 @Mapper 中的 nullValuePropertyMappingStrategy 和 nullValueCheckStrategy。
枚举映射不工作:验证 @ValueMapping 注解是否正确映射源值到目标值。
嵌套映射产生空值:确保嵌套映射器接口也在父映射器中映射。
每周安装量
334
仓库
GitHub 星标数
173
首次出现
2026年2月3日
安全审计
安装于
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github-copilot232
This skill provides patterns for unit testing MapStruct mappers and custom converter classes. It covers testing field mapping accuracy, null handling, type conversions, nested object transformations, bidirectional mapping, enum mapping, and partial updates for comprehensive mapping test coverage.
Use this skill when:
@Mapping annotations with custom expressions work correctly@ValueMapping correctly translates enum values@MappingTarget updates only specified fields<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct</artifactId>
<version>1.5.5.Final</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<scope>test</scope>
</dependency>
dependencies {
implementation("org.mapstruct:mapstruct:1.5.5.Final")
testImplementation("org.junit.jupiter:junit-jupiter")
testImplementation("org.assertj:assertj-core")
}
// Mapper interface
@Mapper(componentModel = "spring")
public interface UserMapper {
UserDto toDto(User user);
User toEntity(UserDto dto);
List<UserDto> toDtos(List<User> users);
}
// Unit test
import org.junit.jupiter.api.Test;
import static org.assertj.core.api.Assertions.*;
class UserMapperTest {
private final UserMapper userMapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMapUserToDto() {
User user = new User(1L, "Alice", "alice@example.com", 25);
UserDto dto = userMapper.toDto(user);
assertThat(dto)
.isNotNull()
.extracting("id", "name", "email", "age")
.containsExactly(1L, "Alice", "alice@example.com", 25);
}
@Test
void shouldMapDtoToEntity() {
UserDto dto = new UserDto(1L, "Alice", "alice@example.com", 25);
User user = userMapper.toEntity(dto);
assertThat(user)
.isNotNull()
.hasFieldOrPropertyWithValue("id", 1L)
.hasFieldOrPropertyWithValue("name", "Alice");
}
@Test
void shouldMapListOfUsers() {
List<User> users = List.of(
new User(1L, "Alice", "alice@example.com", 25),
new User(2L, "Bob", "bob@example.com", 30)
);
List<UserDto> dtos = userMapper.toDtos(users);
assertThat(dtos)
.hasSize(2)
.extracting(UserDto::getName)
.containsExactly("Alice", "Bob");
}
@Test
void shouldHandleNullEntity() {
UserDto dto = userMapper.toDto(null);
assertThat(dto).isNull();
}
}
// Entities with nesting
class User {
private Long id;
private String name;
private Address address;
private List<Phone> phones;
}
// Mapper with nested mapping
@Mapper(componentModel = "spring")
public interface UserMapper {
UserDto toDto(User user);
User toEntity(UserDto dto);
}
// Unit test for nested objects
class NestedObjectMapperTest {
private final UserMapper userMapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMapNestedAddress() {
Address address = new Address("123 Main St", "New York", "NY", "10001");
User user = new User(1L, "Alice", address);
UserDto dto = userMapper.toDto(user);
assertThat(dto.getAddress())
.isNotNull()
.hasFieldOrPropertyWithValue("street", "123 Main St")
.hasFieldOrPropertyWithValue("city", "New York");
}
@Test
void shouldMapListOfNestedPhones() {
List<Phone> phones = List.of(
new Phone("123-456-7890", "MOBILE"),
new Phone("987-654-3210", "HOME")
);
User user = new User(1L, "Alice", null, phones);
UserDto dto = userMapper.toDto(user);
assertThat(dto.getPhones())
.hasSize(2)
.extracting(PhoneDto::getNumber)
.containsExactly("123-456-7890", "987-654-3210");
}
@Test
void shouldHandleNullNestedObjects() {
User user = new User(1L, "Alice", null);
UserDto dto = userMapper.toDto(user);
assertThat(dto.getAddress()).isNull();
}
}
@Mapping Annotations@Mapper(componentModel = "spring")
public interface ProductMapper {
@Mapping(source = "name", target = "productName")
@Mapping(source = "price", target = "salePrice")
@Mapping(target = "discount", expression = "java(product.getPrice() * 0.1)")
ProductDto toDto(Product product);
@Mapping(source = "productName", target = "name")
@Mapping(source = "salePrice", target = "price")
Product toEntity(ProductDto dto);
}
class CustomMappingTest {
private final ProductMapper mapper = Mappers.getMapper(ProductMapper.class);
@Test
void shouldMapFieldsWithCustomNames() {
Product product = new Product(1L, "Laptop", 999.99);
ProductDto dto = mapper.toDto(product);
assertThat(dto)
.hasFieldOrPropertyWithValue("productName", "Laptop")
.hasFieldOrPropertyWithValue("salePrice", 999.99);
}
@Test
void shouldCalculateDiscountFromExpression() {
Product product = new Product(1L, "Laptop", 100.0);
ProductDto dto = mapper.toDto(product);
assertThat(dto.getDiscount()).isEqualTo(10.0);
}
@Test
void shouldReverseMapCustomFields() {
ProductDto dto = new ProductDto(1L, "Laptop", 999.99);
Product product = mapper.toEntity(dto);
assertThat(product)
.hasFieldOrPropertyWithValue("name", "Laptop")
.hasFieldOrPropertyWithValue("price", 999.99);
}
}
// Enum with different representation
enum UserStatus { ACTIVE, INACTIVE, SUSPENDED }
enum UserStatusDto { ENABLED, DISABLED, LOCKED }
@Mapper(componentModel = "spring")
public interface UserMapper {
@ValueMapping(source = "ACTIVE", target = "ENABLED")
@ValueMapping(source = "INACTIVE", target = "DISABLED")
@ValueMapping(source = "SUSPENDED", target = "LOCKED")
UserStatusDto toStatusDto(UserStatus status);
}
class EnumMapperTest {
private final UserMapper mapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMapActiveToEnabled() {
UserStatusDto dto = mapper.toStatusDto(UserStatus.ACTIVE);
assertThat(dto).isEqualTo(UserStatusDto.ENABLED);
}
@Test
void shouldMapSuspendedToLocked() {
UserStatusDto dto = mapper.toStatusDto(UserStatus.SUSPENDED);
assertThat(dto).isEqualTo(UserStatusDto.LOCKED);
}
}
// Custom converter class
public class DateFormatter {
private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
public static String format(LocalDate date) {
return date != null ? date.format(formatter) : null;
}
public static LocalDate parse(String dateString) {
return dateString != null ? LocalDate.parse(dateString, formatter) : null;
}
}
// Unit test
class DateFormatterTest {
@Test
void shouldFormatLocalDateToString() {
LocalDate date = LocalDate.of(2024, 1, 15);
String result = DateFormatter.format(date);
assertThat(result).isEqualTo("2024-01-15");
}
@Test
void shouldParseStringToLocalDate() {
String dateString = "2024-01-15";
LocalDate result = DateFormatter.parse(dateString);
assertThat(result).isEqualTo(LocalDate.of(2024, 1, 15));
}
@Test
void shouldHandleNullInFormat() {
String result = DateFormatter.format(null);
assertThat(result).isNull();
}
@Test
void shouldHandleInvalidDateFormat() {
assertThatThrownBy(() -> DateFormatter.parse("invalid-date"))
.isInstanceOf(DateTimeParseException.class);
}
}
class BidirectionalMapperTest {
private final UserMapper mapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldMaintainDataInRoundTrip() {
User original = new User(1L, "Alice", "alice@example.com", 25);
UserDto dto = mapper.toDto(original);
User restored = mapper.toEntity(dto);
assertThat(restored)
.hasFieldOrPropertyWithValue("id", original.getId())
.hasFieldOrPropertyWithValue("name", original.getName())
.hasFieldOrPropertyWithValue("email", original.getEmail())
.hasFieldOrPropertyWithValue("age", original.getAge());
}
@Test
void shouldPreserveAllFieldsInBothDirections() {
Address address = new Address("123 Main", "NYC", "NY", "10001");
User user = new User(1L, "Alice", "alice@example.com", 25, address);
UserDto dto = mapper.toDto(user);
User restored = mapper.toEntity(dto);
assertThat(restored).usingRecursiveComparison().isEqualTo(user);
}
}
@Mapper(componentModel = "spring")
public interface UserMapper {
void updateEntity(@MappingTarget User entity, UserDto dto);
}
class PartialMapperTest {
private final UserMapper mapper = Mappers.getMapper(UserMapper.class);
@Test
void shouldUpdateExistingEntity() {
User existing = new User(1L, "Alice", "alice@old.com", 25);
UserDto dto = new UserDto(1L, "Alice", "alice@new.com", 26);
mapper.updateEntity(existing, dto);
assertThat(existing)
.hasFieldOrPropertyWithValue("email", "alice@new.com")
.hasFieldOrPropertyWithValue("age", 26);
}
@Test
void shouldNotUpdateFieldsNotInDto() {
User existing = new User(1L, "Alice", "alice@example.com", 25);
UserDto dto = new UserDto(1L, "Bob", null, 0);
mapper.updateEntity(existing, dto);
// Assuming null-aware mapping is configured
assertThat(existing.getEmail()).isEqualTo("alice@example.com");
}
}
@Component for dependency injection@Mapping are not validated at compile timeNull pointer exceptions during mapping : Check nullValuePropertyMappingStrategy and nullValueCheckStrategy in @Mapper.
Enum mapping not working : Verify @ValueMapping annotations correctly map source to target values.
Nested mapping produces null : Ensure nested mapper interfaces are also mapped in parent mapper.
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Repository
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First Seen
Feb 3, 2026
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