DATAGEODE-317 - Add require(..) method to PoolResolver.

spring-data-geode/src/main/java/org/springframework/data/gemfire/client/PoolResolver.java

@@ -21,7 +21,9 @@ import org.apache.geode.cache.Region;
 import org.apache.geode.cache.RegionAttributes;
 import org.apache.geode.cache.client.Pool;
 
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -76,4 +78,23 @@ public interface PoolResolver {
 	 */
 	@Nullable Pool resolve(@Nullable String poolName);
 
+	/**
+	 * Requires a {@link Pool} object with the given {@link String name} to exist.
+	 *
+	 * @param poolName {@link String name} of the required {@link Pool} to resolve.
+	 * @return the required {@link Pool} with the given {@link String name} or throw an {@link IllegalStateException}
+	 * if a {@link Pool} with {@link String name} does not exist!
+	 * @throws IllegalStateException if a {@link Pool} with the given {@link String name} does not exist.
+	 * @see org.apache.geode.cache.client.Pool
+	 * @see #resolve(String)
+	 */
+	default @NonNull Pool require(@NonNull String poolName) {
+
+		Pool pool = resolve(poolName);
+
+		Assert.state(pool != null,
+			() -> String.format("Pool with name [%s] not found", poolName));
+
+		return pool;
+	}
 }

spring-data-geode/src/test/java/org/springframework/data/gemfire/client/PoolResolverUnitTests.java

@@ -17,6 +17,7 @@ package org.springframework.data.gemfire.client;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
@@ -48,6 +49,7 @@ import org.apache.geode.cache.client.Pool;
  * @since 2.3.0
  */
 @RunWith(MockitoJUnitRunner.class)
+@SuppressWarnings("rawtypes")
 public class PoolResolverUnitTests {
 
 	@Mock
@@ -125,6 +127,39 @@ public class PoolResolverUnitTests {
 		verify(mockRegion, times(1)).getAttributes();
 	}
 
+	@Test
+	public void requireExistingPoolReturnsPool() {
+
+		Pool mockPool = mock(Pool.class);
+
+		when(this.testPoolResolver.resolve(anyString())).thenReturn(mockPool);
+		when(this.testPoolResolver.require(anyString())).thenCallRealMethod();
+
+		assertThat(this.testPoolResolver.require("TestPool")).isEqualTo(mockPool);
+
+		verify(this.testPoolResolver, times(1)).resolve(eq("TestPool"));
+	}
+
+	@Test(expected = IllegalStateException.class)
+	public void requireNonExistingPoolThrowsIllegalStateException() {
+
+		when(this.testPoolResolver.require(anyString())).thenCallRealMethod();
+
+		try {
+			this.testPoolResolver.require("MockPool");
+		}
+		catch (IllegalStateException expected) {
+
+			assertThat(expected).hasMessage("Pool with name [MockPool] not found");
+			assertThat(expected).hasNoCause();
+
+			throw expected;
+		}
+		finally {
+			verify(this.testPoolResolver, times(1)).resolve(eq("MockPool"));
+		}
+	}
+
 	private static abstract class TestPoolResolver implements PoolResolver { }
 
 }