Add scale up/down tests.

core/src/test/java/io/atomix/core/AbstractAtomixTest.java

@@ -61,6 +61,13 @@ public static void setupAtomix() throws Exception {
    * Creates an Atomix instance.
    */
   protected static Atomix createAtomix(Node.Type type, int id, Integer... ids) {
+    return createAtomix(ids.length, type, id, ids);
+  }
+
+  /**
+   * Creates an Atomix instance.
+   */
+  protected static Atomix createAtomix(int numPartitions, Node.Type type, int id, Integer... ids) {
     Node localNode = Node.builder(String.valueOf(id))
         .withType(type)
         .withEndpoint(Endpoint.from("localhost", BASE_PORT + id))
@@ -78,6 +85,7 @@ protected static Atomix createAtomix(Node.Type type, int id, Integer... ids) {
         .withDataDirectory(new File("target/test-logs/" + id))
         .withLocalNode(localNode)
         .withBootstrapNodes(bootstrapNodes)
+        .withCoordinationPartitions(numPartitions)
         .withDataPartitions(3) // Lower number of partitions for faster testing
         .build();
   }

core/src/test/java/io/atomix/core/AtomixTest.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * 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
+ *
+ * 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 io.atomix.core;
+
+import io.atomix.cluster.Node;
+import io.atomix.utils.concurrent.Futures;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
+
+/**
+ * Atomix test.
+ */
+public class AtomixTest extends AbstractAtomixTest {
+  private List<Atomix> instances;
+
+  @Before
+  public void setupInstances() throws Exception {
+    deleteData();
+    instances = new ArrayList<>();
+  }
+
+  @After
+  public void teardownInstances() throws Exception {
+    List<CompletableFuture<Void>> futures = instances.stream().map(Atomix::stop).collect(Collectors.toList());
+    try {
+      CompletableFuture.allOf(futures.toArray(new CompletableFuture[futures.size()])).join();
+    } catch (Exception e) {
+      // Do nothing
+    }
+    deleteData();
+  }
+
+  protected CompletableFuture<Atomix> startAtomix(int numPartitions, Node.Type type, int id, Integer... ids) {
+    Atomix atomix = createAtomix(numPartitions, type, id, ids);
+    instances.add(atomix);
+    return atomix.start();
+  }
+
+  /**
+   * Tests scaling up a cluster.
+   */
+  @Test
+  public void testScaleUp() throws Exception {
+    Atomix atomix1 = startAtomix(3, Node.Type.DATA, 1, 1).join();
+    Atomix atomix2 = startAtomix(3, Node.Type.DATA, 2, 1, 2).join();
+    Atomix atomix3 = startAtomix(3, Node.Type.DATA, 3, 1, 2, 3).join();
+  }
+
+  /**
+   * Tests scaling down a cluster.
+   */
+  @Test
+  public void testScaleDown() throws Exception {
+    List<CompletableFuture<Atomix>> futures = new ArrayList<>();
+    futures.add(startAtomix(3, Node.Type.DATA, 1, 1, 2, 3));
+    futures.add(startAtomix(3, Node.Type.DATA, 2, 1, 2, 3));
+    futures.add(startAtomix(3, Node.Type.DATA, 3, 1, 2, 3));
+    Futures.allOf(futures).join();
+    instances.get(0).stop().join();
+    instances.get(1).stop().join();
+    instances.get(2).stop().join();
+  }
+}

protocols/raft/src/main/java/io/atomix/protocols/raft/partition/RaftPartition.java

@@ -144,7 +144,7 @@ CompletableFuture<Void> update(PartitionMetadata metadata, PartitionManagementSe
     if (server == null && metadata.members().contains(managementService.getClusterService().getLocalNode().id())) {
       server = createServer(managementService);
       return server.join(metadata.members());
-    } else if (server != null && server.isRunning()) {
+    } else if (server != null && !metadata.members().contains(managementService.getClusterService().getLocalNode().id())) {
       return server.leave().thenRun(() -> server = null);
     }
     return CompletableFuture.completedFuture(null);