Test back compat of 0.90.6 index

Add back UpgradeReallyOldIndexTest from 1.x, but test 0.90.6 index
(Lucene 4.x) instead of 0.20 (Lucene 3.x), and make sure
only_ancient_segments works.

Closes elastic#10639

src/test/java/org/elasticsearch/bwcompat/StaticIndexBackwardCompatibilityTest.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed to Elasticsearch 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.bwcompat;
+
+import org.apache.lucene.util.LuceneTestCase;
+import org.elasticsearch.action.admin.indices.get.GetIndexResponse;
+import org.elasticsearch.action.search.SearchResponse;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.test.ElasticsearchIntegrationTest;
+
+import java.nio.file.Paths;
+
+import static org.hamcrest.Matchers.greaterThanOrEqualTo;
+
+/**
+ * These tests are against static indexes, built from versions of ES that cannot be upgraded without
+ * a full cluster restart (ie no wire format compatibility).
+ */
+@LuceneTestCase.SuppressCodecs({"Lucene3x", "MockFixedIntBlock", "MockVariableIntBlock", "MockSep", "MockRandom", "Lucene40", "Lucene41", "Appending", "Lucene42", "Lucene45", "Lucene46", "Lucene49"})
+@ElasticsearchIntegrationTest.ClusterScope(scope = ElasticsearchIntegrationTest.Scope.TEST, numDataNodes = 0, minNumDataNodes = 0, maxNumDataNodes = 0)
+public class StaticIndexBackwardCompatibilityTest extends ElasticsearchIntegrationTest {
+
+    public void loadIndex(String index, Object... settings) throws Exception {
+        logger.info("Checking static index " + index);
+        Settings nodeSettings = prepareBackwardsDataDir(Paths.get(getClass().getResource(index + ".zip").toURI()), settings);
+        internalCluster().startNode(nodeSettings);
+        ensureGreen(index);
+        assertIndexSanity(index);
+    }
+
+    private void assertIndexSanity(String index) {
+        GetIndexResponse getIndexResponse = client().admin().indices().prepareGetIndex().get();
+        assertEquals(1, getIndexResponse.indices().length);
+        assertEquals(index, getIndexResponse.indices()[0]);
+        ensureYellow(index);
+        SearchResponse test = client().prepareSearch(index).get();
+        assertThat(test.getHits().getTotalHits(), greaterThanOrEqualTo(1l));
+    }
+
+}

src/test/java/org/elasticsearch/rest/action/admin/indices/upgrade/UpgradeReallyOldIndexTest.java

@@ -0,0 +1,39 @@
+/*
+ * Licensed to Elasticsearch 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.rest.action.admin.indices.upgrade;
+
+import org.elasticsearch.bwcompat.StaticIndexBackwardCompatibilityTest;
+import org.elasticsearch.node.Node;
+
+public class UpgradeReallyOldIndexTest extends StaticIndexBackwardCompatibilityTest {
+
+    public void testUpgrade_0_90_6() throws Exception {
+        String indexName = "index-0.90.6";
+        loadIndex(indexName, Node.HTTP_ENABLED, true);
+
+        UpgradeTest.assertNotUpgraded(httpClient(), indexName);
+        assertTrue(UpgradeTest.hasAncientSegments(httpClient(), indexName));
+        UpgradeTest.runUpgrade(httpClient(), indexName, "wait_for_completion", "true", "only_ancient_segments", "true");
+        assertFalse(UpgradeTest.hasAncientSegments(httpClient(), "index-0.90.6"));
+        // This index has only ancient segments, so it should now be fully upgraded:
+        UpgradeTest.assertUpgraded(httpClient(), indexName);
+    }
+
+}