Tests for CP Membership restart issues

hazelcast/src/test/java/com/hazelcast/cp/internal/CPMemberAddRemoveTest.java

@@ -17,6 +17,7 @@
 package com.hazelcast.cp.internal;
 
 import com.hazelcast.cluster.Address;
+import com.hazelcast.cluster.ClusterState;
 import com.hazelcast.cluster.Member;
 import com.hazelcast.config.Config;
 import com.hazelcast.core.HazelcastInstance;
@@ -401,14 +402,46 @@ public void testExpandRaftGroup() throws ExecutionException, InterruptedExceptio
         instances[3].getCPSubsystem().getCPSubsystemManagementService().promoteToCPMember()
                     .toCompletableFuture().get(30, TimeUnit.SECONDS);
 
-        CPGroupId metadataGroupId = getMetadataGroupId(instances[1]);
-        CPGroup group = instances[1].getCPSubsystem().getCPSubsystemManagementService().getCPGroup(METADATA_CP_GROUP_NAME)
-                                    .toCompletableFuture().get();
+        checkIfInCPGroup(instances[1]);
+    }
+
+    @Test
+    public void contractAndReExpandRaftGroup_leaveTwoRunning() throws ExecutionException, InterruptedException, TimeoutException {
+        HazelcastInstance[] instances = newInstances(3);
+        instances[2].shutdown();
+        assertClusterSizeEventually(2, instances[0], instances[1]);
+        HazelcastInstance hz1 = factory.newHazelcastInstance(createConfig(3, 3));
+        assertClusterStateEventually(ClusterState.ACTIVE, hz1);
+        assertClusterSizeEventually(3, instances[0], instances[1], hz1);
+        hz1.getCPSubsystem().getCPSubsystemManagementService().promoteToCPMember().toCompletableFuture().join();
+        checkIfInCPGroup(hz1);
+    }
+
+    @Test
+    public void contractAndReExpandRaftGroup_leaveOneRunning() throws ExecutionException, InterruptedException, TimeoutException {
+        HazelcastInstance[] instances = newInstances(3);
+        instances[1].shutdown();
+        instances[2].shutdown();
+        assertClusterSizeEventually(1, instances[0]);
+        HazelcastInstance hz1 = factory.newHazelcastInstance(createConfig(3, 3));
+        HazelcastInstance hz2 = factory.newHazelcastInstance(createConfig(3, 3));
+        assertClusterStateEventually(ClusterState.ACTIVE, hz1, hz2);
+        assertClusterSizeEventually(3, instances[0], hz1, hz2);
+        hz1.getCPSubsystem().getCPSubsystemManagementService().promoteToCPMember().toCompletableFuture().join();
+        hz2.getCPSubsystem().getCPSubsystemManagementService().promoteToCPMember().toCompletableFuture().join();
+        checkIfInCPGroup(hz1);
+        checkIfInCPGroup(hz2);
+    }
+
+    private static void checkIfInCPGroup(HazelcastInstance instance) throws InterruptedException, ExecutionException {
+        CPGroupId metadataGroupId = getMetadataGroupId(instance);
+        CPGroup group = instance.getCPSubsystem().getCPSubsystemManagementService().getCPGroup(METADATA_CP_GROUP_NAME)
+                .toCompletableFuture().get();
         assertEquals(3, group.members().size());
         Collection<CPMember> members = group.members();
-        assertTrue(members.contains(instances[3].getCPSubsystem().getLocalCPMember()));
+        assertTrue(members.contains(instance.getCPSubsystem().getLocalCPMember()));
 
-        assertTrueEventually(() -> assertNotNull(getRaftNode(instances[3], metadataGroupId)));
+        assertTrueEventually(() -> assertNotNull(getRaftNode(instance, metadataGroupId)));
     }
 
     @Test

hazelcast/src/test/java/com/hazelcast/cp/internal/CPMemberSplitBrainTest.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2008-2023, Hazelcast, Inc. All Rights Reserved.
+ *
+ * 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 com.hazelcast.cp.internal;
+
+import com.hazelcast.core.HazelcastInstance;
+import com.hazelcast.test.HazelcastParallelParametersRunnerFactory;
+import com.hazelcast.test.HazelcastParametrizedRunner;
+import com.hazelcast.test.annotation.ParallelJVMTest;
+import com.hazelcast.test.annotation.QuickTest;
+import org.junit.experimental.categories.Category;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized.UseParametersRunnerFactory;
+import java.util.UUID;
+
+import static com.hazelcast.cp.internal.HazelcastRaftTestSupport.waitUntilCPDiscoveryCompleted;
+import static org.junit.Assert.assertEquals;
+
+@RunWith(HazelcastParametrizedRunner.class)
+@UseParametersRunnerFactory(HazelcastParallelParametersRunnerFactory.class)
+@Category({QuickTest.class, ParallelJVMTest.class})
+public class CPMemberSplitBrainTest extends RaftSplitBrainTestSupport {
+    @Override
+    protected void onBeforeSplitBrainCreated(HazelcastInstance[] instances) {
+        waitUntilCPDiscoveryCompleted(instances);
+        assertEquals(5, instances[0].getCPSubsystem().getCPSubsystemManagementService()
+                .getCPMembers().toCompletableFuture().join().size());
+    }
+
+    @Override
+    protected void onAfterSplitBrainCreated(HazelcastInstance[] firstBrain, HazelcastInstance[] secondBrain) {
+        UUID uuid = secondBrain[0].getCPSubsystem().getLocalCPMember().getUuid();
+        firstBrain[0].getCPSubsystem().getCPSubsystemManagementService().removeCPMember(uuid).toCompletableFuture().join();
+    }
+
+    @Override
+    protected void onAfterSplitBrainHealed(HazelcastInstance[] instances) throws Exception {
+        assertEqualsEventually(() -> instances[0].getCPSubsystem().getCPSubsystemManagementService()
+                .getCPMembers().toCompletableFuture().join().size(), 5);
+    }
+}