unit-test-exception-handler

Test exception handlers by creating MockMvc tests that invoke controller methods throwing exceptions, then assert HTTP status codes and error response structure. Use @ControllerAdvice with @ExceptionHandler methods to map specific exceptions to standardized error responses, validating both the mapping logic and response format in isolated unit tests.

Use MockMvc to perform requests that trigger exceptions, then assert the returned HTTP status and ErrorResponse DTO fields. Test multiple exception types—ResourceNotFound, Validation, and custom exceptions—to confirm each maps to the correct status code and error message structure.

Yes. MockMvc-based unit tests validate @ExceptionHandler logic in isolation without requiring full application startup. This approach runs faster and focuses specifically on exception-to-response mappings without integration overhead.

Include message localization logic in your GlobalExceptionHandler's @ExceptionHandler methods, then verify localized messages appear in the ErrorResponse DTO during MockMvc tests. Assert that different locales produce expected translated error messages.

Test coverage should include ResourceNotFound, Validation, and any domain-specific custom exceptions your application defines. Each exception type should map to an appropriate HTTP status code and include relevant error details in the standardized error response.

Yes. An ErrorResponse DTO standardizes the structure of all error responses, ensuring consistent formatting across exception types. MockMvc tests verify this DTO contains required fields and correct values for each mapped exception.