levalencia Unit Testing Spring Caching
Overview
This skill provides patterns for unit testing Spring caching annotations (@Cacheable, @CacheEvict, @CachePut) without full Spring context. It covers testing cache behavior, hits/misses, invalidation strategies, cache key generation, and conditional caching using in-memory cache managers.
When to Use
Use this skill when:
- Testing @Cacheable method caching
- Testing @CacheEvict cache invalidation
- Testing @CachePut cache updates
- Verifying cache key generation
- Testing conditional caching
- Want fast caching tests without Redis or cache infrastructure
Instructions
- Use in-memory CacheManager: Use ConcurrentMapCacheManager for tests instead of Redis or other external caches
- Verify repository call counts: Use
times(n)to verify cache hits/misses by counting repository invocations - Test both cache and eviction scenarios: Verify data is cached on first call and evicted when appropriate
- Test cache key generation: Ensure SpEL expressions in
@Cacheable(key = "...")produce correct keys - Test conditional caching: Verify
unlessandconditionparameters work correctly - Clear cache between tests: Reset cache state in @BeforeEach or use @DirtiesContext
- Mock service dependencies: Use mocks for repositories and other services the caching layer uses
- Verify cache behavior explicitly: Don't rely on timing; verify actual cache hit/miss behavior
Examples
Setup: Caching Testing
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>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<scope>test</scope>
</dependency>
Gradle
dependencies {
implementation("org.springframework.boot:spring-boot-starter-cache")
testImplementation("org.springframework.boot:spring-boot-starter-test")
testImplementation("org.mockito:mockito-core")
testImplementation("org.assertj:assertj-core")
}
Basic Pattern: Testing @Cacheable
Cache Hit and Miss Behavior
// Service with caching
@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 caching behavior
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.BeforeEach;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.cache.concurrent.ConcurrentMapCacheManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import static org.mockito.Mockito.*;
import static org.assertj.core.api.Assertions.*;
@Configuration
@EnableCaching
class CacheTestConfig {
@Bean
public CacheManager cacheManager() {
return new ConcurrentMapCacheManager("users");
}
}
class UserServiceCachingTest {
private UserRepository userRepository;
private UserService userService;
private CacheManager cacheManager;
@BeforeEach
void setUp() {
userRepository = mock(UserRepository.class);
cacheManager = new ConcurrentMapCacheManager("users");
userService = new UserService(userRepository);
}
@Test
void shouldCacheUserAfterFirstCall() {
User user = new User(1L, "Alice");
when(userRepository.findById(1L)).thenReturn(Optional.of(user));
User firstCall = userService.getUserById(1L);
User secondCall = userService.getUserById(1L);
assertThat(firstCall).isEqualTo(secondCall);
verify(userRepository, times(1)).findById(1L); // Called only once due to cache
}
@Test
void shouldReturnCachedValueOnSecondCall() {
User user = new User(1L, "Alice");
when(userRepository.findById(1L)).thenReturn(Optional.of(user));
userService.getUserById(1L); // First call - hits database
User cachedResult = userService.getUserById(1L); // Second call - hits cache
assertThat(cachedResult).isEqualTo(user);
verify(userRepository, times(1)).findById(1L);
}
}
Testing @CacheEvict
Cache Invalidation
@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);
}
@CacheEvict(value = "products", allEntries = true)
public void clearAllProducts() {
// Clear entire cache
}
}
class ProductCacheEvictTest {
private ProductRepository productRepository;
private ProductService productService;
private CacheManager cacheManager;
@BeforeEach
void setUp() {
productRepository = mock(ProductRepository.class);
cacheManager = new ConcurrentMapCacheManager("products");
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(1L); // Cache the product
productService.deleteProduct(1L); // Evict from cache
User cachedAfterEvict = userService.getUserById(1L);
// After eviction, repository should be called again
verify(productRepository, times(2)).findById(1L);
}
@Test
void shouldClearAllEntriesFromCache() {
Product product1 = new Product(1L, "Laptop", 999.99);
Product product2 = new Product(2L, "Mouse", 29.99);
when(productRepository.findById(1L)).thenReturn(Optional.of(product1));
when(productRepository.findById(2L)).thenReturn(Optional.of(product2));
productService.getProductById(1L);
productService.getProductById(2L);
productService.clearAllProducts(); // Clear all cache entries
productService.getProductById(1L);
productService.getProductById(2L);
// Repository called twice for each product
verify(productRepository, times(2)).findById(1L);
verify(productRepository, times(2)).findById(2L);
}
}
Testing @CachePut
Cache Update
@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 originalOrder = new Order(1L, "Pending", 100.0);
Order updatedOrder = new Order(1L, "Shipped", 100.0);
when(orderRepository.findById(1L)).thenReturn(Optional.of(originalOrder));
when(orderRepository.save(updatedOrder)).thenReturn(updatedOrder);
orderService.getOrder(1L);
Order result = orderService.updateOrder(updatedOrder);
assertThat(result.getStatus()).isEqualTo("Shipped");
// Next call should return updated version from cache
Order cachedOrder = orderService.getOrder(1L);
assertThat(cachedOrder.getStatus()).isEqualTo("Shipped");
}
}
Testing Conditional Caching
Cache with Conditions
@Service
public class DataService {
private final DataRepository dataRepository;
public DataService(DataRepository dataRepository) {
this.dataRepository = dataRepository;
}
@Cacheable(value = "data", unless = "#result == null")
public Data getData(Long id) {
return dataRepository.findById(id).orElse(null);
}
@Cacheable(value = "users", condition = "#id > 0")
public User getUser(Long id) {
return userRepository.findById(id).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);
// Should call repository twice because null results are not cached
verify(dataRepository, times(2)).findById(999L);
}
@Test
void shouldNotCacheWhenConditionIsFalse() {
UserRepository userRepository = mock(UserRepository.class);
User user = new User(1L, "Alice");
when(userRepository.findById(-1L)).thenReturn(Optional.of(user));
DataService service = new DataService(null);
service.getUser(-1L);
service.getUser(-1L);
// Should call repository twice because id <= 0 doesn't match condition
verify(userRepository, times(2)).findById(-1L);
}
}
Testing Cache Keys
Verify Cache Key Generation
@Service
public class InventoryService {
private final InventoryRepository inventoryRepository;
public InventoryService(InventoryRepository inventoryRepository) {
this.inventoryRepository = inventoryRepository;
}
@Cacheable(value = "inventory", key = "#productId + '-' + #warehouseId")
public InventoryItem getInventory(Long productId, Long warehouseId) {
return inventoryRepository.findByProductAndWarehouse(productId, warehouseId);
}
}
class CacheKeyTest {
@Test
void shouldGenerateCorrectCacheKey() {
InventoryRepository repository = mock(InventoryRepository.class);
InventoryItem item = new InventoryItem(1L, 1L, 100);
when(repository.findByProductAndWarehouse(1L, 1L)).thenReturn(item);
InventoryService service = new InventoryService(repository);
service.getInventory(1L, 1L); // Cache: "1-1"
service.getInventory(1L, 1L); // Hit cache: "1-1"
service.getInventory(2L, 1L); // Miss cache: "2-1"
verify(repository, times(2)).findByProductAndWarehouse(any(), any());
}
}
Best Practices
- Use in-memory CacheManager for unit tests
- Verify repository calls to confirm cache hits/misses
- Test both positive and negative cache scenarios
- Test cache invalidation thoroughly
- Test conditional caching with various conditions
- Keep cache configuration simple in tests
- Mock dependencies that services use
Common Pitfalls
- Testing actual cache infrastructure instead of caching logic
- Not verifying repository call counts
- Forgetting to test cache eviction
- Not testing conditional caching
- Not resetting cache between tests
Constraints and Warnings
- @Cacheable requires a proxy: Spring's caching works via proxies; direct method calls bypass caching
- Cache key collisions: Be aware that different parameters can produce the same cache key if key generation is not specific
- Serialization requirements: Cached objects must be serializable when using distributed caches
- Memory usage: In-memory caches can consume significant memory; consider TTL and max-size settings
- @CachePut vs @Cacheable: @CachePut always executes the method, while @Cacheable skips execution on cache hit
- Null caching: By default, null results are cached unless
unless = "#result == null"is specified - Thread safety: Cache operations should be thread-safe; verify behavior under concurrent access
Troubleshooting
Cache not working in tests: Ensure @EnableCaching is in test configuration.
Wrong cache key generated: Use SpEL syntax correctly in @Cacheable(key = "...").
Cache not evicting: Verify @CacheEvict key matches stored key exactly.