Unit Testing Security and Authorization

Overview

This skill provides patterns for unit testing Spring Security authorization logic using @PreAuthorize, @Secured, @RolesAllowed, and custom permission evaluators. It covers testing role-based access control (RBAC), expression-based authorization, custom permission evaluators, and verifying access denied scenarios without full Spring Security context.

When to Use

Use this skill when:

• Testing @PreAuthorize and @Secured method-level security
• Testing role-based access control (RBAC)
• Testing custom permission evaluators
• Verifying access denied scenarios
• Testing authorization with authenticated principals
• Want fast authorization tests without full Spring Security context

Instructions

Follow these steps to test Spring Security authorization:

1. Set Up Security Testing Dependencies

Add spring-security-test to your test dependencies:

<dependency>
  <groupId>org.springframework.security</groupId>
  <artifactId>spring-security-test</artifactId>
  <scope>test</scope>
</dependency>

2. Enable Method Security in Test Configuration

@Configuration
@EnableMethodSecurity
class TestSecurityConfig { }

3. Test with @WithMockUser

@Test
@WithMockUser(roles = "ADMIN")
void shouldAllowAdminAccess() {
  assertThatCode(() -> service.deleteUser(1L))
    .doesNotThrowAnyException();
}

@Test
@WithMockUser(roles = "USER")
void shouldDenyUserAccess() {
  assertThatThrownBy(() -> service.deleteUser(1L))
    .isInstanceOf(AccessDeniedException.class);
}

4. Test Custom Permission Evaluators

@Test
void shouldGrantPermissionToOwner() {
  Authentication auth = new UsernamePasswordAuthenticationToken(
    "alice", null, List.of(new SimpleGrantedAuthority("ROLE_USER"))
  );
  Document doc = new Document(1L, "Test", new User("alice"));

  boolean result = evaluator.hasPermission(auth, doc, "WRITE");
  assertThat(result).isTrue();
}

5. Validate Security is Active

If tests pass unexpectedly, add this assertion to verify security is enforced:

@Test
void shouldRejectUnauthorizedWhenSecurityEnabled() {
  assertThatThrownBy(() -> service.deleteUser(1L))
    .isInstanceOf(AccessDeniedException.class);
}

Quick Reference

Examples

Basic @PreAuthorize Test

@Service
public class UserService {
  @PreAuthorize("hasRole('ADMIN')")
  public void deleteUser(Long userId) {
    // delete logic
  }
}

// Test
@Test
@WithMockUser(roles = "ADMIN")
void shouldAllowAdminToDeleteUser() {
  assertThatCode(() -> service.deleteUser(1L))
    .doesNotThrowAnyException();
}

@Test
@WithMockUser(roles = "USER")
void shouldDenyUserFromDeletingUser() {
  assertThatThrownBy(() -> service.deleteUser(1L))
    .isInstanceOf(AccessDeniedException.class);
}

Expression-Based Security Test

@PreAuthorize("#userId == authentication.principal.id")
public UserProfile getUserProfile(Long userId) {
  // get profile
}

// For custom principal properties, use @WithUserDetails with a custom UserDetailsService
@Test
@WithUserDetails("alice")
void shouldAllowUserToAccessOwnProfile() {
  assertThatCode(() -> service.getUserProfile(1L))
    .doesNotThrowAnyException();
}

Validation tip: If a security test passes unexpectedly, verify that @EnableMethodSecurity is active on the test configuration — a missing annotation causes all @PreAuthorize checks to be bypassed silently.

See references/basic-testing.md for more basic patterns and references/advanced-authorization.md for complex expressions and custom evaluators.

Best Practices

1. Use `@WithMockUser` for setting authenticated user context
2. Test both allow and deny cases for each security rule
3. Test with different roles to verify role-based decisions
4. Test expression-based security comprehensively
5. Mock external dependencies (permission evaluators, etc.)
6. Test anonymous access separately from authenticated access
7. Use `@EnableGlobalMethodSecurity` in configuration for method-level security

Common Pitfalls

• Forgetting to enable method security in test configuration
• Not testing both allow and deny scenarios
• Testing framework code instead of authorization logic
• Not handling null authentication in tests
• Mixing authentication and authorization tests unnecessarily

Constraints and Warnings

• Method security requires proxy: @PreAuthorize works via proxies; direct method calls bypass security
• `@EnableGlobalMethodSecurity`: Must be enabled for @PreAuthorize, @Secured to work
• Role prefix: Spring adds "ROLE_" prefix automatically; use hasRole('ADMIN') not hasRole('ROLE_ADMIN')
• Authentication context: Security context is thread-local; be careful with async tests
• `@WithMockUser` limitations: Creates a simple Authentication; complex auth scenarios need custom setup
• SpEL expressions: Complex SpEL in @PreAuthorize can be difficult to debug; test thoroughly
• Performance impact: Method security adds overhead; consider security at layer boundaries

References

Setup and Configuration

• [references/setup.md](references/setup.md) - Maven/Gradle dependencies and security configuration

Testing Patterns

• [references/basic-testing.md](references/basic-testing.md) - Basic patterns for @PreAuthorize, @Secured, MockMvc testing, and parameterized tests

Advanced Topics

• [references/advanced-authorization.md](references/advanced-authorization.md) - Expression-based authorization, custom permission evaluators, SpEL expressions

Complete Examples

• [references/complete-examples.md](references/complete-examples.md) - Before/after examples showing transition from manual to declarative security