BAEL-3730: Add example of usage CacheManagerCustomizer in Spring Boot (#9048)

spring-caching/src/test/java/com/baeldung/caching/boot/SimpleCacheCustomizerIntegrationTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.caching.boot;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cache.CacheManager;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class SimpleCacheCustomizerIntegrationTest {
+
+    @Autowired
+    private CacheManager cacheManager;
+
+    @Test
+    public void givenCacheManagerCustomizerWhenBootstrappedThenCacheManagerCustomized() {
+        assertThat(cacheManager.getCacheNames())
+          .containsOnly(SimpleCacheCustomizer.USERS_CACHE, SimpleCacheCustomizer.TRANSACTIONS_CACHE);
+    }
+}