unit-test-caching

name

unit-test-caching

description

Provides patterns for unit testing Spring Cache annotations (@Cacheable, @CachePut, @CacheEvict). Generates test code that mocks cache managers, verifies cache hit/miss behavior, tests cache key generation with SpEL expressions, validates eviction strategies, and checks conditional caching scenarios. Triggers: caching tests, test Spring cache, mock cache, Spring Boot caching, cache hit/miss verification, @Cacheable testing.

Unit Testing Spring Caching

Overview

This skill provides patterns for unit testing Spring caching annotations (@Cacheable, @CacheEvict, @CachePut) without full Spring context. It covers cache hits/misses, invalidation, key generation, and conditional caching using in-memory ConcurrentMapCacheManager.

When to Use

• Writing unit tests for @Cacheable method behavior
• Verifying @CacheEvict cache invalidation works correctly
• Testing @CachePut cache updates
• Validating cache key generation from SpEL expressions
• Testing conditional caching with unless/condition parameters
• Mocking cache managers in fast unit tests without Redis

Instructions

1. Configure in-memory CacheManager: Use ConcurrentMapCacheManager for tests
2. Set up test fixtures: Mock repository and create service instance in @BeforeEach
3. Verify repository call counts: Use times(n) assertions to confirm cache behavior
4. Test cache hit: Call method twice, verify repository called once
5. Test cache miss: Verify repository called on each invocation
6. Test eviction: After @CacheEvict, verify repository called again on next read
7. Test key generation: Verify compound keys from SpEL expressions
8. Validate conditional caching: Test unless (null results) and condition (parameter-based)

Validation checkpoints:

• Run test → If cache not working: verify @EnableCaching annotation present
• If proxy issues: ensure method calls go through Spring proxy (no direct this calls)
• If key mismatches: log actual cache key and compare with @Cacheable(key="...") expression

Examples

Maven

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-cache</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-test</artifactId>
  <scope>test</scope>
</dependency>

Gradle

dependencies {
  implementation("org.springframework.boot:spring-boot-starter-cache")
  testImplementation("org.springframework.boot:spring-boot-starter-test")
}

Testing @Cacheable (Cache Hit/Miss)

// Service
@Service
public class UserService {
  private final UserRepository userRepository;

  public UserService(UserRepository userRepository) {
    this.userRepository = userRepository;
  }

  @Cacheable("users")
  public User getUserById(Long id) {
    return userRepository.findById(id).orElse(null);
  }
}

// Test
class UserServiceCachingTest {

  private UserRepository userRepository;
  private UserService userService;

  @BeforeEach
  void setUp() {
    userRepository = mock(UserRepository.class);
    userService = new UserService(userRepository);
  }

  @Test
  void shouldCacheUserAfterFirstCall() {
    User user = new User(1L, "Alice");
    when(userRepository.findById(1L)).thenReturn(Optional.of(user));

    // First call - hits database
    User firstCall = userService.getUserById(1L);
    // Second call - hits cache
    User   userService.getUserById();

    assertThat(firstCall).isEqualTo(secondCall);
    verify(userRepository, times()).findById(); 
  }

  
    {
    (userRepository.findById()).thenReturn(Optional.of( (, )));

    userService.getUserById();
    userService.getUserById();

    verify(userRepository, times()).findById(); 
  }
}

Testing @CacheEvict

// Service
@Service
public class ProductService {
  private final ProductRepository productRepository;

  public ProductService(ProductRepository productRepository) {
    this.productRepository = productRepository;
  }

  @Cacheable("products")
  public Product getProductById(Long id) {
    return productRepository.findById(id).orElse(null);
  }

  @CacheEvict("products")
  public void deleteProduct(Long id) {
    productRepository.deleteById(id);
  }
}

// Test
class ProductCacheEvictTest {

  private ProductRepository productRepository;
  private ProductService productService;

  @BeforeEach
  void setUp() {
    productRepository = mock(ProductRepository.class);
    productService = new ProductService(productRepository);
  }

  @Test
  void shouldEvictProductFromCacheWhenDeleted() {
    Product product = new Product(1L, "Laptop", 999.99);
    when(productRepository.findById(1L)).thenReturn(Optional.of(product));

    productService.getProductById(); 
    productService.deleteProduct(); 

    
    productService.getProductById();
    verify(productRepository, times()).findById();
  }

  
    {
        (, , );
        (, , );
    (productRepository.findById(anyLong())).thenAnswer(i ->
      Optional.of( (i.getArgument(), , )));

    productService.getProductById();
    productService.getProductById();

    
    productService.clearAllProducts();

    productService.getProductById();
    productService.getProductById();

    verify(productRepository, times()).findById(anyLong());
  }
}

Testing @CachePut

@Service
public class OrderService {
  private final OrderRepository orderRepository;

  public OrderService(OrderRepository orderRepository) {
    this.orderRepository = orderRepository;
  }

  @Cacheable("orders")
  public Order getOrder(Long id) {
    return orderRepository.findById(id).orElse(null);
  }

  @CachePut(value = "orders", key = "#order.id")
  public Order updateOrder(Order order) {
    return orderRepository.save(order);
  }
}

class OrderCachePutTest {

  private OrderRepository orderRepository;
  private OrderService orderService;

  @BeforeEach
  void setUp() {
    orderRepository = mock(OrderRepository.class);
    orderService = new OrderService(orderRepository);
  }

  @Test
  void shouldUpdateCacheWhenOrderIsUpdated() {
    Order original = new Order(1L, "Pending", 100.0);
    Order updated = new Order(, , );

    (orderRepository.findById()).thenReturn(Optional.of(original));
    (orderRepository.save(updated)).thenReturn(updated);

    orderService.getOrder();
    orderService.updateOrder(updated);

    
       orderService.getOrder();
    assertThat(cachedOrder.getStatus()).isEqualTo();
  }
}

Testing Conditional Caching

@Service
public class DataService {
  private final DataRepository dataRepository;

  public DataService(DataRepository dataRepository) {
    this.dataRepository = dataRepository;
  }

  // Don't cache null results
  @Cacheable(value = "data", unless = "#result == null")
  public Data getData(Long id) {
    return dataRepository.findById(id).orElse(null);
  }

  // Only cache when id > 0
  @Cacheable(value = "users", condition = "#id > 0")
  public User getUser(Long id) {
    return dataRepository.findById(id).map(u -> new User(u.getId(), u.getName())).orElse(null);
  }
}

class ConditionalCachingTest {

  @Test
  void shouldNotCacheNullResults() {
    DataRepository dataRepository = mock(DataRepository.class);
    when(dataRepository.findById(999L)).thenReturn(Optional.empty());
    DataService service = new DataService(dataRepository);

    service.getData(999L);
    service.getData(999L);

    verify(dataRepository, times(2)).findById(999L); 
  }

  
    {
       mock(DataRepository.class);
    (dataRepository.findById(-)).thenReturn(Optional.of( (-, )));

        (dataRepository);

    service.getUser(-);
    service.getUser(-);

    verify(dataRepository, times()).findById(-); 
  }
}

Testing Cache Keys with SpEL

@Service
public class InventoryService {
  private final InventoryRepository inventoryRepository;

  public InventoryService(InventoryRepository inventoryRepository) {
    this.inventoryRepository = inventoryRepository;
  }

  // Compound key: productId-warehouseId
  @Cacheable(value = "inventory", key = "#productId + '-' + #warehouseId")
  public InventoryItem getInventory(Long productId, Long warehouseId) {
    return inventoryRepository.findByProductAndWarehouse(productId, warehouseId);
  }
}

class CacheKeyTest {

  @Test
  void shouldUseCorrectCacheKeyForDifferentCombinations() {
    InventoryRepository repository = mock(InventoryRepository.class);
    InventoryItem item = new InventoryItem(1L, 1L, 100);
    when(repository.findByProductAndWarehouse(1L, 1L)).thenReturn(item);

    InventoryService service = new InventoryService(repository);

    // Same key: "1-1" - should cache
    service.getInventory(1L, 1L);
    service.getInventory(1L, 1L); 
    verify(repository, times()).findByProductAndWarehouse(, );

    
    service.getInventory(, ); 
    verify(repository, times()).findByProductAndWarehouse(any(), any());
  }
}

Best Practices

• Mock repository calls: Use verify(mock, times(n)) to assert cache behavior
• Test both hit and miss scenarios: Don't just test the happy path
• Clear cache state: Reset between tests to avoid flaky results
• Use ConcurrentMapCacheManager: Fast, no external dependencies
• Verify eviction: Always test that @CacheEvict actually invalidates cached data

Constraints and Warnings

• @Cacheable requires proxy: Direct method calls (this.method()) bypass caching - use dependency injection
• Cache key collisions: Compound keys from SpEL must be unique per dataset
• Null caching: Null results are cached by default - use unless = "#result == null" to exclude
• @CachePut always executes: Unlike @Cacheable, it always runs the method
• Memory usage: In-memory caches grow unbounded - consider TTL for long-running tests
• Thread safety: ConcurrentMapCacheManager is thread-safe; distributed caches may require additional config

Troubleshooting

Issue	Solution
Cache not working	Verify @EnableCaching on test config
Proxy bypass	Use autowired/constructor injection, not direct this calls
Key mismatch	Log cache key with cache.getNativeKey() to debug SpEL
Flaky tests	Clear cache in @BeforeEach before each test

References

• Spring Caching Documentation
• Cacheable Annotation
• SpEL Expressions

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