Addendum for YARN-5548. Use MockRMMemoryStateStore to reduce test failures (Bibin A Chundatt via Varun Saxena)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/MockRMMemoryStateStore.java

@@ -0,0 +1,32 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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
+ *
+ *     http://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.apache.hadoop.yarn.server.resourcemanager;
+
+import org.apache.hadoop.yarn.event.EventHandler;
+import org.apache.hadoop.yarn.server.resourcemanager.recovery.MemoryRMStateStore;
+
+/**
+ * Test helper for MemoryRMStateStore will make sure the event.
+ */
+public class MockRMMemoryStateStore extends MemoryRMStateStore {
+  @SuppressWarnings("rawtypes")
+  @Override
+  protected EventHandler getRMStateStoreEventHandler() {
+    return rmStateStoreEventHandler;
+  }
+}