Add UT for helper

Signed-off-by: Rishab Nahata <rnnahata@amazon.com>

server/src/test/java/org/opensearch/action/admin/cluster/configuration/VotingConfigExclusionsHelperTests.java

@@ -0,0 +1,96 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.action.admin.cluster.configuration;
+
+import org.junit.BeforeClass;
+import org.opensearch.Version;
+import org.opensearch.cluster.ClusterName;
+import org.opensearch.cluster.ClusterState;
+import org.opensearch.cluster.coordination.CoordinationMetadata;
+import org.opensearch.cluster.metadata.Metadata;
+import org.opensearch.cluster.node.DiscoveryNode;
+import org.opensearch.cluster.node.DiscoveryNodeRole;
+import org.opensearch.cluster.node.DiscoveryNodes;
+import org.opensearch.common.Strings;
+import org.opensearch.common.unit.TimeValue;
+import org.opensearch.test.OpenSearchTestCase;
+
+import java.util.Set;
+
+import static java.util.Collections.emptyMap;
+import static java.util.Collections.emptySet;
+import static java.util.Collections.singleton;
+import static org.opensearch.action.admin.cluster.configuration.VotingConfigExclusionsHelper.addExclusionAndGetState;
+import static org.opensearch.action.admin.cluster.configuration.VotingConfigExclusionsHelper.clearExclusionsAndGetState;
+import static org.opensearch.action.admin.cluster.configuration.VotingConfigExclusionsHelper.resolveVotingConfigExclusionsAndCheckMaximum;
+
+public class VotingConfigExclusionsHelperTests extends OpenSearchTestCase {
+
+    private static DiscoveryNode localNode, otherNode1, otherNode2, otherDataNode;
+    private static CoordinationMetadata.VotingConfigExclusion localNodeExclusion, otherNode1Exclusion, otherNode2Exclusion;
+    private static ClusterState initialClusterState;
+
+    public void testAddExclusionAndGetState() {
+        ClusterState updatedState = addExclusionAndGetState(initialClusterState, Set.of(localNodeExclusion), 2);
+        assertTrue(updatedState.coordinationMetadata().getVotingConfigExclusions().contains(localNodeExclusion));
+        assertEquals(1, updatedState.coordinationMetadata().getVotingConfigExclusions().size());
+    }
+
+    public void testResolveVotingConfigExclusions() {
+        AddVotingConfigExclusionsRequest request = new AddVotingConfigExclusionsRequest(
+            Strings.EMPTY_ARRAY,
+            new String[]{"other1"},
+            Strings.EMPTY_ARRAY,
+            TimeValue.timeValueSeconds(30)
+        );
+        Set<CoordinationMetadata.VotingConfigExclusion> votingConfigExclusions = resolveVotingConfigExclusionsAndCheckMaximum(request, initialClusterState, 10);
+        assertEquals(1, votingConfigExclusions.size());
+        assertTrue(votingConfigExclusions.contains(otherNode1Exclusion));
+    }
+
+    public void testResolveVotingConfigExclusionFailsWhenLimitExceeded() {
+        AddVotingConfigExclusionsRequest request = new AddVotingConfigExclusionsRequest(
+            Strings.EMPTY_ARRAY,
+            new String[]{"other1", "other2"},
+            Strings.EMPTY_ARRAY,
+            TimeValue.timeValueSeconds(30)
+        );
+        expectThrows(
+            IllegalArgumentException.class,
+            () -> resolveVotingConfigExclusionsAndCheckMaximum(request, initialClusterState, 1)
+        );
+    }
+
+    public void testClearExclusionAndGetState() {
+        ClusterState updatedState = addExclusionAndGetState(initialClusterState, Set.of(localNodeExclusion), 2);
+        assertTrue(updatedState.coordinationMetadata().getVotingConfigExclusions().contains(localNodeExclusion));
+        updatedState = clearExclusionsAndGetState(updatedState);
+        assertTrue(updatedState.coordinationMetadata().getVotingConfigExclusions().isEmpty());
+    }
+
+    @BeforeClass
+    public static void createBaseClusterState() {
+        localNode = makeDiscoveryNode("local");
+        localNodeExclusion = new CoordinationMetadata.VotingConfigExclusion(localNode);
+        otherNode1 = makeDiscoveryNode("other1");
+        otherNode1Exclusion = new CoordinationMetadata.VotingConfigExclusion(otherNode1);
+        otherNode2 = makeDiscoveryNode("other2");
+        otherNode2Exclusion = new CoordinationMetadata.VotingConfigExclusion(otherNode2);
+        otherDataNode = new DiscoveryNode("data", "data", buildNewFakeTransportAddress(), emptyMap(), emptySet(), Version.CURRENT);
+        final CoordinationMetadata.VotingConfiguration allNodesConfig = CoordinationMetadata.VotingConfiguration.of(localNode, otherNode1, otherNode2);
+        initialClusterState = ClusterState.builder(new ClusterName("cluster"))
+            .nodes(new DiscoveryNodes.Builder().add(localNode).add(otherNode1).add(otherNode2).add(otherDataNode).localNodeId(localNode.getId()).clusterManagerNodeId(localNode.getId()))
+            .metadata(Metadata.builder().coordinationMetadata(CoordinationMetadata.builder().lastAcceptedConfiguration(allNodesConfig).lastCommittedConfiguration(allNodesConfig).build()))
+            .build();
+    }
+
+    private static DiscoveryNode makeDiscoveryNode(String name) {
+        return new DiscoveryNode(name, name, buildNewFakeTransportAddress(), emptyMap(), singleton(DiscoveryNodeRole.CLUSTER_MANAGER_ROLE), Version.CURRENT);
+    }
+}