Fix for issue 358 from Tomaz Solc. Don't return a NaN when comparing two 0-length word lists.

git-svn-id: http://google-refine.googlecode.com/svn/trunk@2088 7d457c2a-affb-35e4-300a-418c747d4874

main/src/com/google/refine/model/recon/StandardReconConfig.java

@@ -429,6 +429,10 @@ public class StandardReconConfig extends ReconConfig {
     }
     
     static protected double wordDistance(Set<String> longWords, Set<String> shortWords) {
+        if (longWords.size() == 0) {
+            return 0.0;
+        }
+
         double common = 0;
         for (String word : shortWords) {
             if (longWords.contains(word)) {

main/tests/server/src/com/google/refine/tests/model/ReconTests.java

@@ -0,0 +1,46 @@
+package com.google.refine.tests.model;
+
+import java.util.ArrayList;
+
+import org.slf4j.LoggerFactory;
+import org.testng.Assert;
+import org.testng.annotations.BeforeTest;
+import org.testng.annotations.Test;
+
+import com.google.refine.model.recon.StandardReconConfig;
+import com.google.refine.tests.RefineTest;
+
+public class ReconTests extends RefineTest {
+
+    @BeforeTest
+    public void init() {
+        logger = LoggerFactory.getLogger(this.getClass());
+    }
+
+    private class StandardReconConfigTest extends StandardReconConfig {
+        public StandardReconConfigTest() {
+            super("", "", "", "", "", false, new ArrayList<ColumnDetail>());
+        }
+
+        public double wordDistanceTest(String s1, String s2) {
+            return wordDistance(s1, s2);
+        }
+    }
+
+    @Test
+    public void wordDistance() {
+        StandardReconConfigTest t = new StandardReconConfigTest();
+        double r = t.wordDistanceTest("Foo", "Foo bar");
+
+        Assert.assertEquals(r,0.5);
+    }
+
+    @Test
+    public void wordDistanceOnlyStopwords() {
+        StandardReconConfigTest t = new StandardReconConfigTest();
+        double r = t.wordDistanceTest("On and On", "On and On and On");
+
+        Assert.assertTrue(!Double.isInfinite(r));
+        Assert.assertTrue(!Double.isNaN(r));
+    }
+}