缓存配置类Mock失败，求正确的单元测试实现方案

问题背景 #

我需要为尚未Mock缓存配置属性类的可缓存层编写单元测试，自己实现的测试类运行时抛出异常，请求排查修复。

原缓存配置代码（CacheConfig.java） #

import com.github.benmanes.caffeine.cache.Caffeine;

@Configuration
@EnableCaching
public class CacheConfig {
    private final CacheProperties cacheProperties;

    public CacheConfig(CacheProperties cacheProperties) {
        this.cacheProperties = cacheProperties;
    }
    
    @Bean
    @ConditionalOnProperty(name = "spring.cache.type", havingValue = "caffeine")
    public Caffeine<Object, Object> caffeineConfig() {
        return Caffeine.from(cacheProperties.getCaffeine().getSpec());
    }
}

原测试代码（CacheConfigTest.java） #

@SpringBootTest(classes = CacheConfig.class)
public class CacheConfigTest {

    @MockBean
    private CacheProperties cacheProperties;

    @MockBean
    private CacheManager cacheManager;

    @InjectMocks
    private CacheConfig cacheConfig;

    @Value("${spring.cache.type}")
    private String cacheType;

    @BeforeEach
    void setUp() {
        // Mock the behavior of cacheProperties
        when(cacheProperties.getCaffeine()).thenReturn(new CacheProperties.Caffeine());
        when(cacheProperties.getCaffeine().getSpec()).thenReturn("expireAfterWrite=10m");
    }

    @Test
    void testCaffeineConfigBeanCreationWhenCacheTypeIsCaffeine() {
        // Arrange
        System.setProperty("spring.cache.type", "caffeine");

        // Act
        Caffeine<Object, Object> caffeine = cacheConfig.caffeineConfig();

        // Assert
        assertThat(caffeine).isNotNull();
        verify(cacheProperties, times(1)).getCaffeine();
    }

    @Test
    void testCaffeineConfigBeanNotCreatedWhenCacheTypeIsNotCaffeine() {
        // Arrange
        System.setProperty("spring.cache.type", "other");

        // Act
        Caffeine<Object, Object> caffeine = cacheConfig.caffeineConfig();

        // Assert
        assertThat(caffeine).isNull();
    }
}

异常栈信息 #

Caused by: java.lang.IllegalStateException: No CacheResolver specified, and no bean of type CacheManager found. Register a CacheManager bean or remove the @EnableCaching annotation from your configuration.
    at org.springframework.cache.interceptor.CacheAspectSupport.afterSingletonsInstantiated(CacheAspectSupport.java:277) ~[spring-context-6.1.6.jar:6.1.6]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:986) ~[spring-beans-6.1.6.jar:6.1.6]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:962) ~[spring-context-6.1.6.jar:6.1.6]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:624) ~[spring-context-6.1.6.jar:6.1.6]

问题分析 #

1. 条件注解未生效：直接调用caffeineConfig()方法属于普通方法调用，@ConditionalOnProperty是Spring容器创建Bean时才会触发的条件校验，手动调用不会触发该逻辑，所以第二个测试中caffeine不会为null。
2. 上下文初始化冲突：@SpringBootTest启动Spring上下文时，@EnableCaching要求容器中必须存在CacheManager或CacheResolver Bean。虽然添加了@MockBean CacheManager，但同时使用@InjectMocks手动实例化CacheConfig，导致上下文初始化逻辑和手动实例化逻辑冲突。
3. 属性设置方式错误：用System.setProperty设置属性的时机不对，Spring上下文启动后修改系统属性无法触发配置刷新，属性不会生效。

修复方案 #

方案1：纯单元测试（验证方法逻辑，无需启动Spring上下文） #

适合快速测试caffeineConfig()方法的业务逻辑，仅用Mockito模拟依赖：

import com.github.benmanes.caffeine.cache.Caffeine;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;
import org.springframework.boot.autoconfigure.cache.CacheProperties;
import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.Mockito.*;

@ExtendWith(MockitoExtension.class)
public class CacheConfigTest {

    @Mock
    private CacheProperties cacheProperties;

    @InjectMocks
    private CacheConfig cacheConfig;

    @BeforeEach
    void setUp() {
        CacheProperties.Caffeine caffeineProps = new CacheProperties.Caffeine();
        caffeineProps.setSpec("expireAfterWrite=10m");
        when(cacheProperties.getCaffeine()).thenReturn(caffeineProps);
    }

    @Test
    void caffeineConfig_returnsValidCaffeineInstance() {
        // Act
        Caffeine<Object, Object> caffeine = cacheConfig.caffeineConfig();

        // Assert
        assertThat(caffeine).isNotNull();
        verify(cacheProperties, times(1)).getCaffeine();
        verify(cacheProperties.getCaffeine(), times(1)).getSpec();
    }
}

方案2：条件验证测试（启动Spring上下文，验证Bean创建逻辑） #

适合测试@ConditionalOnProperty的生效逻辑，验证不同缓存类型下Bean是否正确创建：

import com.github.benmanes.caffeine.cache.Caffeine;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.boot.autoconfigure.cache.CacheProperties;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.TestPropertySource;
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatThrownBy;
import static org.mockito.Mockito.when;

@SpringBootTest(classes = CacheConfig.class)
public class CacheConfigConditionalTest {

    @MockBean
    private CacheProperties cacheProperties;

    private final ApplicationContext applicationContext;

    public CacheConfigConditionalTest(ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
    }

    @BeforeEach
    void setUp() {
        CacheProperties.Caffeine caffeineProps = new CacheProperties.Caffeine();
        caffeineProps.setSpec("expireAfterWrite=10m");
        when(cacheProperties.getCaffeine()).thenReturn(caffeineProps);
    }

    @Test
    @TestPropertySource(properties = "spring.cache.type=caffeine")
    void caffeineConfigBeanExistsWhenCacheTypeIsCaffeine() {
        Caffeine<Object, Object> caffeine = applicationContext.getBean(Caffeine.class);
        assertThat(caffeine).isNotNull();
    }

    @Test
    @TestPropertySource(properties = "spring.cache.type=other")
    void caffeineConfigBeanDoesNotExistWhenCacheTypeIsNotCaffeine() {
        assertThatThrownBy(() -> applicationContext.getBean(Caffeine.class))
                .isInstanceOf(NoSuchBeanDefinitionException.class);
    }
}

关键修复点 #

• 移除@InjectMocks和手动调用方法的逻辑，改用Spring上下文获取Bean来验证条件注解效果；
• 使用@TestPropertySource设置测试属性，确保Spring上下文能正确读取配置；
• 拆分测试场景：纯单元测试验证方法逻辑，上下文测试验证条件Bean创建逻辑，职责更清晰。

内容的提问来源于stack exchange，提问作者TechGeek