Protect against no stems

2 files changed, 16 insertions, 20 deletions

diff --git a/container-search/src/main/java/com/yahoo/prelude/querytransform/StemmingSearcher.java b/container-search/src/main/java/com/yahoo/prelude/querytransform/StemmingSearcher.java
index fd37329eebc..9050b82fd69 100644
--- a/container-search/src/main/java/com/yahoo/prelude/querytransform/StemmingSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/querytransform/StemmingSearcher.java
@@ -193,9 +193,10 @@ public class StemmingSearcher extends Searcher {
         Item blockAsItem = (Item)current;
         CompositeItem composite;
         List<StemList> segments = linguistics.getStemmer().stem(current.stringValue(), index.getStemMode(), context.language);
+        if (segments.isEmpty()) return blockAsItem;
+
         String indexName = current.getIndexName();
         Substring substring = getOffsets(current);
-
         if (segments.size() == 1) {
             TaggableItem w = singleWordSegment(current, segments.get(0), index, substring, context.insidePhrase);
             setMetaData(current, context.reverseConnectivity, w);
diff --git a/container-search/src/test/java/com/yahoo/prelude/querytransform/test/StemmingSearcherTestCase.java b/container-search/src/test/java/com/yahoo/prelude/querytransform/test/StemmingSearcherTestCase.java
index bcb243b4563..118adae40ca 100644
--- a/container-search/src/test/java/com/yahoo/prelude/querytransform/test/StemmingSearcherTestCase.java
+++ b/container-search/src/test/java/com/yahoo/prelude/querytransform/test/StemmingSearcherTestCase.java
@@ -23,7 +23,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
- * @author <a href="mailto:mathiasm@yahoo-inc.com">Mathias M. Lidal</a>
+ * @author Mathias M. Lidal
  */
 public class StemmingSearcherTestCase {
 
@@ -33,8 +33,8 @@ public class StemmingSearcherTestCase {
 
     @Test
     void testStemOnlySomeTerms() {
-        assertStem("/search?query=Holes in CVS and Subversion nostem:Found",
-                "WEAKAND(100) hole in cvs and subversion nostem:Found");
+        assertStemmed("WEAKAND(100) hole in cvs and subversion nostem:Found", "/search?query=Holes in CVS and Subversion nostem:Found"
+                     );
     }
 
     @Test
@@ -78,7 +78,7 @@ public class StemmingSearcherTestCase {
 
     @Test
     void testDontStemPrefixes() {
-        assertStem("/search?query=ist*&language=de", "WEAKAND(100) ist*");
+        assertStemmed("WEAKAND(100) ist*", "/search?query=ist*&language=de");
     }
 
     @Test
@@ -90,10 +90,10 @@ public class StemmingSearcherTestCase {
 
     @Test
     void testNounStemming() {
-        assertStem("/search?query=noun:towers noun:tower noun:tow",
-                "WEAKAND(100) noun:tower noun:tower noun:tow");
-        assertStem("/search?query=notnoun:towers notnoun:tower notnoun:tow",
-                "WEAKAND(100) notnoun:tower notnoun:tower notnoun:tow");
+        assertStemmed("WEAKAND(100) noun:tower noun:tower noun:tow", "/search?query=noun:towers noun:tower noun:tow"
+                     );
+        assertStemmed("WEAKAND(100) notnoun:tower notnoun:tower notnoun:tow", "/search?query=notnoun:towers notnoun:tower notnoun:tow"
+                     );
     }
 
     @SuppressWarnings("deprecation")
@@ -133,11 +133,10 @@ public class StemmingSearcherTestCase {
 
     @Test
     void testMultipleStemming() {
-        Query q = new Query(QueryTestCase.httpEncode("/search?language=en&search=four&query=trees \"nouns girls\" flowers \"a verbs a\" girls&default-index=foobar"));
-        executeStemming(q);
-        assertEquals("WEAKAND(100) WORD_ALTERNATIVES foobar:[ tree(0.7) trees(1.0) ] " +
-                "foobar:\"noun girl\" WORD_ALTERNATIVES foobar:[ flower(0.7) flowers(1.0) ] " +
-                "foobar:\"a verb a\" WORD_ALTERNATIVES foobar:[ girl(0.7) girls(1.0) ]", q.getModel().getQueryTree().getRoot().toString());
+        assertStemmed("WEAKAND(100) WORD_ALTERNATIVES foobar:[ tree(0.7) trees(1.0) ] " +
+                      "foobar:\"noun girl\" WORD_ALTERNATIVES foobar:[ flower(0.7) flowers(1.0) ] " +
+                      "foobar:\"a verb a\" WORD_ALTERNATIVES foobar:[ girl(0.7) girls(1.0) ]",
+                      "/search?language=en&search=four&query=trees \"nouns girls\" flowers \"a verbs a\" girls&default-index=foobar");
     }
 
     private Execution.Context newExecutionContext() {
@@ -153,12 +152,8 @@ public class StemmingSearcherTestCase {
                       newExecutionContext()).search(query);
     }
 
-    private void assertStem(String queryString, String expectedQueryTree) {
-        assertStemEncoded(QueryTestCase.httpEncode(queryString), expectedQueryTree);
-    }
-
-    private void assertStemEncoded(String encodedQueryString, String expectedQueryTree) {
-        Query query = new Query(encodedQueryString);
+    private void assertStemmed(String expectedQueryTree, String queryString) {
+        Query query = new Query(QueryTestCase.httpEncode(queryString));
         executeStemming(query);
         assertEquals(expectedQueryTree, query.getModel().getQueryTree().getRoot().toString());
     }