fix AbstractParser.singleList not adding null strings

- prevents null titles in oo... parser  (as detected by ParserTest)
- correct ParserTest dc_description check (dc_description allowed to return 0 length array)

source/net/yacy/document/AbstractParser.java

@@ -92,7 +92,7 @@ public abstract class AbstractParser implements Parser {
 
     public static List<String> singleList(String t) {
         List<String> c = new ArrayList<String>(1);
-        c.add(t);
+        if (t != null) c.add(t);
         return c;
     }
 

test/net/yacy/document/ParserTest.java

@@ -49,7 +49,7 @@ public class ParserTest {
                             assertThat(str.toString(), containsString("In München steht ein Hofbräuhaus, dort gibt es Bier in Maßkrügen"));
                             assertThat(doc.dc_title(), containsString(testFile[2]));
                             assertThat(doc.dc_creator(), containsString(testFile[3]));
-                            assertThat(doc.dc_description()[0], containsString(testFile[4]));
+                            if (testFile[4].length() > 0) assertThat(doc.dc_description()[0], containsString(testFile[4]));
                         }
                     } catch (final InterruptedException ex) {}
                     }
@@ -81,9 +81,9 @@ public class ParserTest {
 
                             System.out.println("Parsed " + filename + ": " + str);
                             assertThat(str.toString(), containsString("In München steht ein Hofbräuhaus, dort gibt es Bier in Maßkrügen"));
-                     //       assertThat(doc.dc_title(), containsString(testFile[2]));
+                            assertThat(doc.dc_title(), containsString(testFile[2]));
                             assertThat(doc.dc_creator(), containsString(testFile[3]));
-                            assertThat(doc.dc_description()[0], containsString(testFile[4]));
+                            if (testFile[4].length() > 0) assertThat(doc.dc_description()[0], containsString(testFile[4]));
                         }
                     } catch (final InterruptedException ex) {}
                     }
@@ -115,7 +115,7 @@ public class ParserTest {
                             assertThat(str.toString(), containsString("In München steht ein Hofbräuhaus, dort gibt es Bier in Maßkrügen"));
                             assertThat(doc.dc_title(), containsString(testFile[2]));
                             assertThat(doc.dc_creator(), containsString(testFile[3]));
-                            assertThat(doc.dc_description()[0], containsString(testFile[4]));
+                            if (testFile[4].length() > 0) assertThat(doc.dc_description()[0], containsString(testFile[4]));
                         }
                     } catch (final InterruptedException ex) {}
                     }
@@ -147,7 +147,7 @@ public class ParserTest {
                             assertThat(str.toString(), containsString("In München steht ein Hofbräuhaus, dort gibt es Bier in Maßkrügen"));
                             assertThat(doc.dc_title(), containsString(testFile[2]));
                             assertThat(doc.dc_creator(), containsString(testFile[3]));
-                            assertThat(doc.dc_description()[0], containsString(testFile[4]));
+                            if (testFile[4].length() > 0) assertThat(doc.dc_description()[0], containsString(testFile[4]));
                         }
                     } catch (final InterruptedException ex) {}
                     }