DATAGEODE-318 - Add CacheResolver implementation that resolves a single, configured GemFireCache instance.

spring-data-geode/src/main/java/org/springframework/data/gemfire/support/SingleCacheCacheResolver.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.gemfire.support;
+
+import org.apache.geode.cache.Cache;
+import org.apache.geode.cache.GemFireCache;
+import org.apache.geode.cache.client.ClientCache;
+
+import org.springframework.data.gemfire.CacheResolver;
+import org.springframework.lang.Nullable;
+
+/**
+ * {@link CacheResolver} implementation that resolves to a configured, single {@link GemFireCache} instance.
+ *
+ * @author John Blum
+ * @see org.apache.geode.cache.Cache
+ * @see org.apache.geode.cache.GemFireCache
+ * @see org.apache.geode.cache.client.ClientCache
+ * @since 2.3.0
+ */
+public abstract class SingleCacheCacheResolver {
+
+	/**
+	 * Factory method used to resolve a single, configured instance of a {@literal peer} {@link Cache}.
+	 *
+	 * @param cache {@link Cache} to resolve.
+	 * @return a single, configured instance of a {@literal peer} {@link Cache}.
+	 * @see org.springframework.data.gemfire.CacheResolver
+	 * @see org.apache.geode.cache.Cache
+	 */
+	public static CacheResolver<Cache> from(@Nullable Cache cache) {
+		return () -> cache;
+	}
+
+	/**
+	 * Factory method used to resolve a single, configured instance of a {@literal peer} {@link ClientCache}.
+	 *
+	 * @param clientCache {@link ClientCache} to resolve.
+	 * @return a single, configured instance of a {@literal peer} {@link ClientCache}.
+	 * @see org.springframework.data.gemfire.CacheResolver
+	 * @see org.apache.geode.cache.client.ClientCache
+	 */
+	public static CacheResolver<ClientCache> from(@Nullable ClientCache clientCache) {
+		return () -> clientCache;
+	}
+}

spring-data-geode/src/test/java/org/springframework/data/gemfire/support/SingleCacheCacheResolverUnitTests.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.gemfire.support;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verifyNoInteractions;
+
+import org.junit.Test;
+
+import org.apache.geode.cache.Cache;
+import org.apache.geode.cache.client.ClientCache;
+
+import org.springframework.data.gemfire.CacheResolver;
+
+/**
+ * Unit Tests for {@link SingleCacheCacheResolver}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.apache.geode.cache.Cache
+ * @see org.apache.geode.cache.client.ClientCache
+ * @see org.springframework.data.gemfire.CacheResolver
+ * @see org.springframework.data.gemfire.support.SingleCacheCacheResolver
+ * @since 2.3.0
+ */
+public class SingleCacheCacheResolverUnitTests {
+
+	@Test
+	public void fromCacheReturnsCacheResolverResolvingCache() {
+
+		Cache mockCache = mock(Cache.class);
+
+		CacheResolver<Cache> cacheResolver = SingleCacheCacheResolver.from(mockCache);
+
+		assertThat(cacheResolver).isNotNull();
+		assertThat(cacheResolver.resolve()).isSameAs(mockCache);
+
+		verifyNoInteractions(mockCache);
+	}
+
+	@Test
+	public void fromNullCacheReturnsCacheResolverReturningNull() {
+
+		CacheResolver<Cache> cacheResolver = SingleCacheCacheResolver.from((Cache) null);
+
+		assertThat(cacheResolver).isNotNull();
+		assertThat(cacheResolver.resolve()).isNull();
+	}
+
+	@Test
+	public void fromClientCacheReturnsCacheResolverResolvingClientCache() {
+
+		ClientCache mockClientCache = mock(ClientCache.class);
+
+		CacheResolver<ClientCache> clientCacheResolver = SingleCacheCacheResolver.from(mockClientCache);
+
+		assertThat(clientCacheResolver).isNotNull();
+		assertThat(clientCacheResolver.resolve()).isSameAs(mockClientCache);
+
+		verifyNoInteractions(mockClientCache);
+	}
+
+	@Test
+	public void fromNullClientCacheReturnsCacheResolverReturningNull() {
+
+		CacheResolver<ClientCache> cacheResolver = SingleCacheCacheResolver.from((ClientCache) null);
+
+		assertThat(cacheResolver).isNotNull();
+		assertThat(cacheResolver.resolve()).isNull();
+	}
+}