unit-test-exception-handler

SKILL.md

Unit testing patterns for Spring @ExceptionHandler and @ControllerAdvice global exception handlers.

Test exception-to-error-response transformations and HTTP status codes using MockMvc with setControllerAdvice() to register handlers

Verify error response structure includes required fields (timestamp, status, error, message) and test field-level validation errors from MethodArgumentNotValidException

Cover multiple exception types with appropriate status codes (404, 409, 401, 403, 500) and test logging or side effects triggered by handlers

Use mock test controllers that throw exceptions to trigger handler behavior without full integration test overhead

Unit Testing ExceptionHandler and ControllerAdvice

Overview

This skill provides patterns for writing unit tests for Spring Boot exception handlers. It covers testing @ExceptionHandler methods in @ControllerAdvice classes using MockMvc, including HTTP status assertions, JSON response validation, field-level validation error testing, and mocking handler dependencies.

When to Use

Writing unit tests for @ExceptionHandler methods

Testing @ControllerAdvice global exception handling

Validating REST API error response formatting

Mocking exceptions in controller tests

Testing field-level validation error responses

Asserting custom error payloads and HTTP status codes

Instructions