introduced NodeSettingsSource in the test infrastructure os tests with scopes TEST & SUITE without an explicit numNodes definitions will fall back on the nodeSettings(int) callback

src/test/java/org/elasticsearch/test/AbstractIntegrationTest.java

@@ -20,8 +20,6 @@ package org.elasticsearch.test;
 
 import com.carrotsearch.randomizedtesting.SeedUtils;
 import com.google.common.base.Joiner;
-import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableMap.Builder;
 import com.google.common.collect.Iterators;
 import org.apache.lucene.util.AbstractRandomizedTest.IntegrationTests;
 import org.apache.lucene.util.IOUtils;
@@ -595,12 +593,24 @@ public abstract class AbstractIntegrationTest extends ElasticSearchTestCase {
     
     protected TestCluster buildTestCluster(Scope scope) {
         long currentClusterSeed = randomLong();
-        Builder<Integer, Settings> ordinalMap = ImmutableMap.builder();
         int numNodes = getNumNodes();
+        NodeSettingsSource nodeSettingsSource;
+        if (numNodes > 0) {
+            NodeSettingsSource.Immutable.Builder nodesSettings = NodeSettingsSource.Immutable.builder();
             for (int i = 0; i < numNodes; i++) {
-            ordinalMap.put(i, nodeSettings(i));
+                nodesSettings.set(i, nodeSettings(i));
             }
-        return new TestCluster(currentClusterSeed, getNumNodes(), TestCluster.clusterName(scope.name(), ElasticSearchTestCase.CHILD_VM_ID, currentClusterSeed), ordinalMap.build());
+            nodeSettingsSource = nodesSettings.build();
+        } else {
+            nodeSettingsSource = new NodeSettingsSource() {
+                @Override
+                public Settings settings(int nodeOrdinal) {
+                    return nodeSettings(nodeOrdinal);
+                }
+            };
+        }
+
+        return new TestCluster(currentClusterSeed, numNodes, TestCluster.clusterName(scope.name(), ElasticSearchTestCase.CHILD_VM_ID, currentClusterSeed), nodeSettingsSource);
     }
     
     @Retention(RetentionPolicy.RUNTIME)

src/test/java/org/elasticsearch/test/NodeSettingsSource.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch 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.elasticsearch.test;
+
+import com.google.common.collect.ImmutableMap;
+import org.elasticsearch.common.settings.Settings;
+
+import java.util.Map;
+
+public abstract class NodeSettingsSource {
+
+    public static final NodeSettingsSource EMPTY = new NodeSettingsSource() {
+        @Override
+        public Settings settings(int nodeOrdinal) {
+            return null;
+        }
+    };
+
+    /**
+     * @return  the settings for the node represented by the given ordinal, or {@code null} if there are not settings defined (in which
+     *          case a random settings will be generated for the node)
+     */
+    public abstract Settings settings(int nodeOrdinal);
+
+    public static class Immutable extends NodeSettingsSource {
+
+        private final Map<Integer, Settings> settingsPerNode;
+
+        private Immutable(Map<Integer, Settings> settingsPerNode) {
+            this.settingsPerNode = settingsPerNode;
+        }
+
+        public static Builder builder() {
+            return new Builder();
+        }
+
+        @Override
+        public Settings settings(int nodeOrdinal) {
+            return settingsPerNode.get(nodeOrdinal);
+        }
+
+        public static class Builder {
+
+            private final ImmutableMap.Builder<Integer, Settings> settingsPerNode = ImmutableMap.builder();
+
+            private Builder() {
+            }
+
+            public Builder set(int ordinal, Settings settings) {
+                settingsPerNode.put(ordinal, settings);
+                return this;
+            }
+
+            public Immutable build() {
+                return new Immutable(settingsPerNode.build());
+            }
+
+        }
+    }
+}

src/test/java/org/elasticsearch/test/TestCluster.java

@@ -94,14 +94,13 @@ public class TestCluster implements Closeable, Iterable<Client> {
 
     private double transportClientRatio = 0.0;
 
-    private final Map<Integer, Settings> perNodeSettingsMap;
-    private static final Map<Integer, Settings> EMPTY = Collections.emptyMap();
+    private final NodeSettingsSource nodeSettingsSource;
 
     public TestCluster(long clusterSeed, String clusterName) {
-        this(clusterSeed, -1, clusterName, EMPTY);
+        this(clusterSeed, -1, clusterName, NodeSettingsSource.EMPTY);
     }
 
-    public TestCluster(long clusterSeed, int numNodes, String clusterName, Map<Integer, Settings> perNodeSettings) {
+    public TestCluster(long clusterSeed, int numNodes, String clusterName, NodeSettingsSource nodeSettingsSource) {
         this.clusterName = clusterName;
         Random random = new Random(clusterSeed);
         numSharedNodes = numNodes == -1 ? 2 + random.nextInt(4) : numNodes; // at least 2 nodes if randomized
@@ -129,12 +128,12 @@ public class TestCluster implements Closeable, Iterable<Client> {
                         // default to non gateway
                 .put("gateway.type", "none")
                 .build();
-        this.perNodeSettingsMap = perNodeSettings;
+        this.nodeSettingsSource = nodeSettingsSource;
     }
 
     private Settings getSettings(int nodeOrdinal, Settings others) {
         Builder builder = ImmutableSettings.settingsBuilder().put(defaultSettings);
-        Settings settings = perNodeSettingsMap.get(nodeOrdinal);
+        Settings settings = nodeSettingsSource.settings(nodeOrdinal);
         if (settings != null) {
             builder.put(settings);
         }