unit-test-exception-handler

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

giuseppe-trisciuoglio/developer-kit|Updated Apr 8, 2026

Works with

Claude CodeCursorClineWindsurfCodexGoose

What it does

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)

Repository

giuseppe-trisciuoglio/developer-kit

Last updated

Apr 8, 2026

Installation Guide

Select your AI agent

How to use unit-test-exception-handler on Cursor

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Prerequisites

Before installing skills in Cursor, ensure your development environment meets these requirements:

›Cursor installed and configured on your machine
›Node.js 16+ with npm — verify with node --version
›Active project directory where you want to add unit-test-exception-handler

Run the install command

Execute the skills CLI command in your project's root directory to begin installation:

$npx skills add https://github.com/giuseppe-trisciuoglio/developer-kit --skill unit-test-exception-handler

Fetches unit-test-exception-handler from giuseppe-trisciuoglio/developer-kit and configures it for Cursor.

Select Cursor when prompted

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Verify installation

Confirm successful installation by checking the skill directory location:

.cursor/skills/unit-test-exception-handler

Restart Cursor to activate unit-test-exception-handler. Access via /unit-test-exception-handler in your agent's command palette.

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Use Cases

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Generate reports, summarize documents, draft communications

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Quality Improvement

Enhance output quality through reviews, suggestions, and refinements

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Review drafts, suggest improvements, catch errors

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Improve work quality by 30-40% with less effort

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.

Instructions

Create a test controller that throws specific exceptions to trigger each @ExceptionHandler

Register ControllerAdvice via setControllerAdvice() on MockMvcBuilders.standaloneSetup()

Assert HTTP status codes with .andExpect(status().isXxx())

Verify error response fields using jsonPath("$.field") matchers

Test validation errors by sending invalid payloads and checking MethodArgumentNotValidException produces field-level details

Debug failures with .andDo(print()) — if handler not invoked, verify setControllerAdvice() is called and exception type matches

Examples

Exception Handler and Error DTO

@ControllerAdvice public class GlobalExceptionHandler { @ExceptionHandler(ResourceNotFoundException.class) @ResponseStatus(HttpStatus.NOT_FOUND) public ErrorResponse handleNotFound(ResourceNotFoundException ex) { return new ErrorResponse(404, "Not Found", ex.getMessage()); } @ExceptionHandler(ValidationException.class) @ResponseStatus(HttpStatus.BAD_REQUEST) public ErrorResponse handleValidation(ValidationException ex) { return new ErrorResponse(400, "Bad Request", ex.getMessage()); } @ExceptionHandler(MethodArgumentNotValidException.class) @ResponseStatus(HttpStatus.BAD_REQUEST) public ValidationErrorResponse handleMethodArgumentNotValid(MethodArgumentNotValidException ex) { Map<String, String> errors = new HashMap<>(); ex.getBindingResult().getFieldErrors().forEach(e -> errors.put(e.getField(), e.getDefaultMessage())); return new ValidationErrorResponse(400, "Validation Failed", errors); } } public record ErrorResponse(int status, String error, String message) {} public record ValidationErrorResponse(int status, String error, Map<String, String> errors) {}

Unit Test

@ExtendWith(MockitoExtension.class) class GlobalExceptionHandlerTest { private MockMvc mockMvc; @BeforeEach void setUp() { GlobalExceptionHandler handler = new GlobalExceptionHandler(); mockMvc = MockMvcBuilders.standaloneSetup(new TestController()) .setControllerAdvice(handler) .build(); } @Test void shouldReturn404WhenResourceNotFound() throws Exception { mockMvc.perform(get("/api/users/999")) .andExpect(status().isNotFound()) .andExpect(jsonPath("$.status").value(404)) .andExpect(jsonPath("$.error").value("Not Found")) .andExpect(jsonPath("$.message").value("User not found")); } @Test void shouldReturn400WithFieldErrorsOnValidationFailure() throws Exception { mockMvc.perform(post("/api/users") .contentType("application/json") .content("{\"name\":\"\",\"email\":\"invalid\"}")) .andExpect(status().isBadRequest()) .andExpect(jsonPath("$.status").value(400)) .andExpect(jsonPath("$.errors.name").value("must not be blank")) .andExpect(jsonPath("$.errors.email").value("must be a valid email")); } } @RestController @RequestMapping("/api") class TestController { @GetMapping("/users/{id}") public User getUser(@PathVariable Long id) { throw new ResourceNotFoundException("User not found"); } @PostMapping("/users") public User createUser(@RequestBody @Valid User user) { throw new ValidationException("Validation failed"); } }

Best Practices

Test each @ExceptionHandler method independently with a dedicated exception throw

Assert all fields in the error response body, not just the HTTP status

For validation errors, verify both the field name key and the error message value

Use MockMvcBuilders.standaloneSetup() for isolated handler tests without full Spring context

Log assertion failures: chain .andDo(print()) to print request/response when a test fails

Common Pitfalls

Handler not invoked: ensure setControllerAdvice() is called on the builder

JsonPath mismatch: use .andDo(print()) to inspect actual response structure

Status is 200: missing @ResponseStatus on the handler method

Duplicate handlers: @Order controls precedence; more specific exception types take priority

Testing handler logic instead of behavior: mock external dependencies, test only the response transformation

unit-test-exception-handler

What it does

Category

Repository

Last updated

Installation Guide

How to use unit-test-exception-handler on Cursor

Prerequisites

Run the install command

Select Cursor when prompted

Verify installation

Security Notice

Documentation

List & Monetize Your Skill

Use Cases

Task Automation & Efficiency

Knowledge Enhancement

Quality Improvement

Install Skill

Unit Testing ExceptionHandler and ControllerAdvice

Overview

When to Use

Instructions

Examples

Exception Handler and Error DTO

Unit Test

Best Practices

Common Pitfalls

Constraints and Warnings

Implementation Guide

Best Practices

When to Use This

Learning Path

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