unit▌

Unit testing patterns for MapStruct mappers and custom converters with comprehensive transformation validation. \n \n Covers field mapping accuracy, null handling, type conversions, nested objects, bidirectional mapping, enum mapping, and partial updates \n Includes Maven and Gradle setup with MapStruct, JUnit 5, and AssertJ dependencies \n Provides patterns for testing simple mappings, nested hierarchies, custom @Mapping annotations, enum @ValueMapping , and @MappingTarget partial updates \n De

Unit testing REST controllers in isolation with MockMvc and mocked service dependencies. \n \n Covers testing all HTTP methods (GET, POST, PUT, PATCH, DELETE) with status code and response body validation using JsonPath assertions \n Includes patterns for request parameter binding, validation errors, exception handling, and content negotiation across different Accept and Content-Type headers \n Uses standalone MockMvc setup with Mockito to mock service layer dependencies, keeping tests focused o

Unit testing patterns for Spring @ExceptionHandler and @ControllerAdvice global exception handlers. \n \n Test exception-to-error-response transformations and HTTP status codes using MockMvc with setControllerAdvice() to register handlers \n Verify error response structure includes required fields (timestamp, status, error, message) and test field-level validation errors from MethodArgumentNotValidException \n Cover multiple exception types with appropriate status codes (404, 409, 401, 403, 500)

JUnit 5 patterns for testing utility classes, static methods, and pure functions without mocking complexity. \n \n Covers testing strategies for string manipulation, calculations, collections, data validation, and format utilities with edge case and boundary condition handling \n Uses AssertJ assertions for readable test code and @ParameterizedTest for testing multiple similar scenarios efficiently \n Emphasizes null handling, empty inputs, extreme values, and floating-point precision as critica

Unit testing JSON serialization and deserialization with Spring's @JsonTest and Jackson. \n \n Covers serialization/deserialization of POJOs, custom serializers/deserializers, field name mappings with @JsonProperty , and null handling using JacksonTester for type-safe assertions \n Includes patterns for testing nested objects, lists, date/time formatting, and polymorphic types with @JsonTypeInfo \n Provides Maven and Gradle setup, best practices for avoiding circular references and null inclusio

Unit test external REST API integrations with WireMock HTTP mocking and request verification. \n \n Stub HTTP responses with configurable status codes, headers, and JSON bodies; verify request details including headers, query parameters, and request bodies \n Test error scenarios (4xx/5xx responses, timeouts, malformed responses) without calling real APIs or hitting rate limits \n Use dynamic port allocation to avoid conflicts in parallel test execution; automatic cleanup between tests via JUnit

Isolated unit testing patterns for Spring service layer using Mockito and JUnit 5. \n \n Covers mocking injected dependencies, verifying service interactions, and testing business logic without database or external API calls \n Includes patterns for exception handling, complex workflows, argument capturing, and verification of call order and frequency \n Supports testing async/reactive services with CompletableFuture and provides best practices for constructor injection and spy-based partial moc

Use this skill to create or review unit tests for Vue components, composables, and Pinia stores. Keep tests small, deterministic, and behavior-first.

Systematic JUnit 5 patterns for testing numeric limits, null/empty cases, and edge conditions. \n \n Covers numeric boundaries (Integer.MIN_VALUE, MAX_VALUE, zero), string edge cases (null, empty, whitespace), and collection sizes (empty, single, many) \n Includes parameterized test examples using @ParameterizedTest and @ValueSource for efficient multi-case coverage \n Demonstrates floating-point precision testing with tolerance-based assertions, overflow/underflow detection, and special values

Unit testing Jakarta Bean Validation constraints and custom validators without Spring context. \n \n Covers testing built-in constraints ( @NotNull , @Email , @Min , @Max , @Size ) and custom @Constraint implementations with violation assertion patterns \n Includes cross-field validation, validation groups for conditional rules, and parameterized test scenarios for multiple inputs \n Provides setup patterns using Validation.buildDefaultValidatorFactory().getValidator() and assertion helpers to e