Further tweak AutoFollowIT#testAutoFollowManyIndices:

* reduce the number of leader indices to be auto followed
* also check the number of follower indices being created
* also check the whether leader indices are marked as auto followed

Relates to #36761

x-pack/plugin/ccr/src/test/java/org/elasticsearch/xpack/ccr/AutoFollowIT.java

@@ -35,7 +35,9 @@ import java.util.List;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
+import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.notNullValue;
+import static org.hamcrest.Matchers.nullValue;
 
 public class AutoFollowIT extends CcrIntegTestCase {
 
@@ -131,7 +133,7 @@ public class AutoFollowIT extends CcrIntegTestCase {
             .build();
 
         putAutoFollowPatterns("my-pattern", new String[] {"logs-*"});
-        long numIndices = randomIntBetween(4, 16);
+        long numIndices = randomIntBetween(4, 8);
         for (int i = 0; i < numIndices; i++) {
             createLeaderIndex("logs-" + i, leaderIndexSettings);
         }
@@ -140,8 +142,12 @@ public class AutoFollowIT extends CcrIntegTestCase {
         AutoFollowStats[] autoFollowStats = new AutoFollowStats[1];
         try {
             assertBusy(() -> {
-                metaData[0] = followerClient().admin().cluster().prepareState().get().getState().metaData();
+                metaData[0] = getFollowerCluster().clusterService().state().metaData();
                 autoFollowStats[0] = getAutoFollowStats();
+
+                assertThat(metaData[0].indices().size(), equalTo((int) expectedVal1));
+                AutoFollowMetadata autoFollowMetadata = metaData[0].custom(AutoFollowMetadata.TYPE);
+                assertThat(autoFollowMetadata.getFollowedLeaderIndexUUIDs().get("my-pattern"), hasSize((int) expectedVal1));
                 assertThat(autoFollowStats[0].getNumberOfSuccessfulFollowIndices(), equalTo(expectedVal1));
             });
         } catch (AssertionError ae) {
@@ -155,8 +161,12 @@ public class AutoFollowIT extends CcrIntegTestCase {
         deleteAutoFollowPatternSetting();
         try {
             assertBusy(() -> {
-                metaData[0] = followerClient().admin().cluster().prepareState().get().getState().metaData();
+                metaData[0] = getFollowerCluster().clusterService().state().metaData();
                 autoFollowStats[0] = getAutoFollowStats();
+
+                assertThat(metaData[0].indices().size(), equalTo((int )expectedVal1));
+                AutoFollowMetadata autoFollowMetadata = metaData[0].custom(AutoFollowMetadata.TYPE);
+                assertThat(autoFollowMetadata.getFollowedLeaderIndexUUIDs().get("my-pattern"), nullValue());
                 assertThat(autoFollowStats[0].getAutoFollowedClusters().size(), equalTo(0));
             });
         } catch (AssertionError ae) {
@@ -176,8 +186,14 @@ public class AutoFollowIT extends CcrIntegTestCase {
 
         try {
             assertBusy(() -> {
-                metaData[0] = followerClient().admin().cluster().prepareState().get().getState().metaData();
+                metaData[0] = getFollowerCluster().clusterService().state().metaData();
                 autoFollowStats[0] = getAutoFollowStats();
+
+                assertThat(metaData[0].indices().size(), equalTo((int) expectedVal2));
+                AutoFollowMetadata autoFollowMetadata = metaData[0].custom(AutoFollowMetadata.TYPE);
+                // expectedVal2 + 1, because logs-does-not-count is also marked as auto followed.
+                // (This is because indices created before a pattern exists are not auto followed and are just marked as such.)
+                assertThat(autoFollowMetadata.getFollowedLeaderIndexUUIDs().get("my-pattern"), hasSize((int) expectedVal2 + 1));
                 long count = Arrays.stream(metaData[0].getConcreteAllIndices()).filter(s -> s.startsWith("copy-")).count();
                 assertThat(count, equalTo(expectedVal2));
                 // Ensure that there are no auto follow errors: