CacheLoader tests

guava/src/test/java/org/baeldung/guava/GuavaCacheLoaderTest.java

@@ -0,0 +1,71 @@
+package org.baeldung.guava;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Iterables;
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.util.Map;
+import java.util.concurrent.ExecutionException;
+
+import static com.google.common.collect.Iterables.cycle;
+import static com.google.common.collect.Maps.newHashMap;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class GuavaCacheLoaderTest {
+    int callCount = 0;
+
+    @Test
+    public void givenAMap_whenAddingValues_thenCanTreatThemAsCache() {
+        Map<String, String> cache = newHashMap();
+        cache.put("foo", "cachedValueForFoo");
+        cache.put("bar", "cachedValueForBar");
+
+        assertThat(cache.get("foo")).isEqualTo("cachedValueForFoo");
+        assertThat(cache.get("bar")).isEqualTo("cachedValueForBar");
+    }
+
+    @Test
+    public void givenCacheLoader_whenGettingItemTwice_shouldOnlyCallOnce() throws ExecutionException {
+
+        final LoadingCache<String, String> loadingCache = CacheBuilder.newBuilder()
+            .build(new CacheLoader<String, String>() {
+                @Override
+                public String load(final String s) throws Exception {
+                    return slowMethod(s);
+                }
+            });
+
+        String value = loadingCache.get("key");
+        value = loadingCache.get("key");
+
+        assertThat(callCount).isEqualTo(1);
+        assertThat(value).isEqualTo("key");
+    }
+
+    @Test
+    public void givenCacheLoader_whenRefreshingItem_shouldCallAgain() throws ExecutionException {
+
+        final LoadingCache<String, String> loadingCache = CacheBuilder.newBuilder()
+            .build(new CacheLoader<String, String>() {
+                @Override
+                public String load(final String s) throws Exception {
+                    return slowMethod(s);
+                }
+            });
+
+        String value = loadingCache.get("key");
+        loadingCache.refresh("key");
+
+        assertThat(callCount).isEqualTo(2);
+        assertThat(value).isEqualTo("key");
+    }
+
+    private String slowMethod(final String s) {
+        callCount++;
+        return s;
+    }
+}