#12901: add TestBackwardsCompatibility test case that reveals the block tree IntersectTermsEnum bug #12895 (#12913)

* #12901: add TestBackwardsCompatibility test case that reveals the block tree IntersectTermsEnum bug #12895

* woops, forgot to tidy up

* #12901: Ignore failing test; reflow text to workaround spotless' poor text formatting skills

lucene/backward-codecs/src/test/org/apache/lucene/backward_index/TestBackwardsCompatibility.java

@@ -109,6 +109,7 @@ import org.apache.lucene.search.Sort;
 import org.apache.lucene.search.SortField;
 import org.apache.lucene.search.TermQuery;
 import org.apache.lucene.search.TopDocs;
+import org.apache.lucene.search.WildcardQuery;
 import org.apache.lucene.store.ByteBuffersDirectory;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.FSDirectory;
@@ -127,6 +128,7 @@ import org.apache.lucene.util.InfoStream;
 import org.apache.lucene.util.Version;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
+import org.junit.Ignore;
 
 /*
   Verify we can read previous versions' indexes, do searches
@@ -2240,6 +2242,26 @@ public class TestBackwardsCompatibility extends LuceneTestCase {
     }
   }
 
+  // #12895: test on a carefully crafted 9.8.0 index (from a small contiguous subset
+  // of wikibigall unique terms) that shows the read-time exception of
+  // IntersectTermsEnum (used by WildcardQuery)
+  @Ignore("re-enable once we merge #12900")
+  public void testWildcardQueryExceptions990() throws IOException {
+    Path path = createTempDir("12895");
+
+    String name = "index.12895.9.8.0.zip";
+    InputStream resource = TestBackwardsCompatibility.class.getResourceAsStream(name);
+    assertNotNull("missing zip file to reproduce #12895", resource);
+    TestUtil.unzip(resource, path);
+
+    try (Directory dir = newFSDirectory(path);
+        DirectoryReader reader = DirectoryReader.open(dir)) {
+      IndexSearcher searcher = new IndexSearcher(reader);
+
+      searcher.count(new WildcardQuery(new Term("field", "*qx*")));
+    }
+  }
+
   @Nightly
   public void testReadNMinusTwoCommit() throws IOException {
     for (String name : binarySupportedNames) {