Try to throw an exception with the end of the log file if the coref benchmark test doesn't work as expected

Author: AngledLuffa

itest/src/edu/stanford/nlp/dcoref/DcorefBenchmarkSlowITest.java

@@ -6,6 +6,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.StringReader;
+import java.util.List;
 import java.util.Properties;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -130,6 +131,14 @@ public static Counter<String> getCorefResults(String resultsString) throws IOExc
       }
     }
 
+    if (results.keySet().isEmpty()) {
+      List<String> lines = StringUtils.split(resultsString, "\\R");
+      int start = Math.max(0, lines.size() - 20);
+      lines = lines.subList(start, lines.size() - start);
+      String tail = StringUtils.join(lines, "\n");
+      throw new RuntimeException("Coref output did not have any results in it!  The end of the log is as follows:\n" + tail);
+    }
+
     return results;
   }