Fix biblatex cleanup for date field

CHANGELOG.md

@@ -36,6 +36,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - Fixed [#2311](https://github.com/JabRef/jabref/issues/2311): The DBLP fetcher has been rewritten and is working again.
 - Fixed [#2273](https://github.com/JabRef/jabref/issues/2273): Export via commandline in no-gui mode is now working again.
 - We fixed an issue when JabRef restored its session and a shared database was used: The error message "No suitable driver found" will not appear.
+- We fixed an issue where the BibLaTeX Cleanup did not move the contents of the fields `year` and `month` to the field `date`. [#2335](https://github.com/JabRef/jabref/issues/2335)
 
 ### Removed
 

src/main/java/net/sf/jabref/logic/cleanup/BiblatexCleanup.java

@@ -3,14 +3,15 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 
 import net.sf.jabref.model.FieldChange;
 import net.sf.jabref.model.cleanup.CleanupJob;
 import net.sf.jabref.model.entry.BibEntry;
 import net.sf.jabref.model.entry.EntryConverter;
 import net.sf.jabref.model.entry.FieldName;
 
+import org.apache.commons.lang3.StringUtils;
+
 /**
  * Converts the entry to BibLatex format.
  */
@@ -25,32 +26,25 @@ public List<FieldChange> cleanup(BibEntry entry) {
             entry.getField(oldFieldName).ifPresent(oldValue -> {
                 if (!oldValue.isEmpty() && (!entry.getField(newFieldName).isPresent())) {
                     // There is content in the old field and no value in the new, so just copy
-                    entry.setField(newFieldName, oldValue);
-                    changes.add(new FieldChange(entry, newFieldName, null, oldValue));
-
-                    entry.clearField(oldFieldName);
-                    changes.add(new FieldChange(entry, oldFieldName, oldValue, null));
+                    changes.add(entry.setField(newFieldName, oldValue).orElse(null));
+                    changes.add(entry.clearField(oldFieldName).orElse(null));
                 }
             });
         }
-
         // Dates: create date out of year and month, save it and delete old fields
-        entry.getField(FieldName.DATE).ifPresent(date -> {
-            if (date.isEmpty()) {
-                entry.getFieldOrAlias(FieldName.DATE).ifPresent(newDate -> {
-                    Optional<String> oldYear = entry.getField(FieldName.YEAR);
-                    Optional<String> oldMonth = entry.getField(FieldName.MONTH);
-
-                    entry.setField(FieldName.DATE, newDate);
-                    entry.clearField(FieldName.YEAR);
-                    entry.clearField(FieldName.MONTH);
-
-                    changes.add(new FieldChange(entry, FieldName.DATE, null, newDate));
-                    changes.add(new FieldChange(entry, FieldName.YEAR, oldYear.orElse(null), null));
-                    changes.add(new FieldChange(entry, FieldName.MONTH, oldMonth.orElse(null), null));
-                });
-            }
-        });
+        // If there already exists a value for the field date, it is not overwritten
+        String date = "";
+        if (entry.getField(FieldName.DATE).isPresent()) {
+            date = entry.getField(FieldName.DATE).get();
+        }
+        if (StringUtils.isBlank(date)) {
+            entry.getFieldOrAlias(FieldName.DATE).ifPresent(newDate -> {
+                changes.add(entry.setField(FieldName.DATE, newDate).orElse(null));
+                changes.add(entry.clearField(FieldName.YEAR).orElse(null));
+                changes.add(entry.clearField(FieldName.MONTH).orElse(null));
+            });
+        }
         return changes;
     }
+
 }

src/test/java/net/sf/jabref/logic/cleanup/BiblatexCleanupTest.java

@@ -0,0 +1,50 @@
+package net.sf.jabref.logic.cleanup;
+
+import java.util.Optional;
+
+import net.sf.jabref.model.entry.BibEntry;
+import net.sf.jabref.model.entry.FieldName;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+public class BiblatexCleanupTest {
+
+    @Rule
+    public TemporaryFolder bibFolder = new TemporaryFolder();
+
+    private BiblatexCleanup worker;
+
+    @Before
+    public void setUp() {
+        worker = new BiblatexCleanup();
+    }
+
+    @Test
+    public void convertToBiblatexMovesYearMonthToDate() {
+        BibEntry entry = new BibEntry();
+        entry.setField(FieldName.YEAR, "2011");
+        entry.setField(FieldName.MONTH, "#jan#");
+
+        worker.cleanup(entry);
+        Assert.assertEquals(Optional.empty(), entry.getField(FieldName.YEAR));
+        Assert.assertEquals(Optional.empty(), entry.getField(FieldName.MONTH));
+        Assert.assertEquals(Optional.of("2011-01"), entry.getField(FieldName.DATE));
+    }
+
+    @Test
+    public void convertToBiblatexDateAlreadyPresent() {
+        BibEntry entry = new BibEntry();
+        entry.setField(FieldName.YEAR, "2011");
+        entry.setField(FieldName.MONTH, "#jan#");
+        entry.setField(FieldName.DATE, "2012");
+
+        worker.cleanup(entry);
+        Assert.assertEquals(Optional.of("2011"), entry.getField(FieldName.YEAR));
+        Assert.assertEquals(Optional.of("#jan#"), entry.getField(FieldName.MONTH));
+        Assert.assertEquals(Optional.of("2012"), entry.getField(FieldName.DATE));
+    }
+}

src/test/java/net/sf/jabref/logic/cleanup/CleanupWorkerTest.java

@@ -24,6 +24,7 @@
 import net.sf.jabref.model.database.BibDatabase;
 import net.sf.jabref.model.database.BibDatabaseContext;
 import net.sf.jabref.model.entry.BibEntry;
+import net.sf.jabref.model.entry.FieldName;
 import net.sf.jabref.model.entry.FileField;
 import net.sf.jabref.model.entry.ParsedFileField;
 import net.sf.jabref.model.metadata.MetaData;
@@ -48,7 +49,6 @@ public class CleanupWorkerTest {
     private CleanupWorker worker;
     private File pdfFolder;
 
-
     @Before
     public void setUp() throws IOException {
         pdfFolder = bibFolder.newFolder();
@@ -288,7 +288,8 @@ public void cleanupCasesAddsBracketAroundAluminiumGalliumArsenid() {
                         Collections.emptyList(), Collections.emptyList()));
         Assert.assertNotEquals(Collections.emptyList(), protectedTermsLoader.getProtectedTerms());
         CleanupPreset preset = new CleanupPreset(new FieldFormatterCleanups(true,
-                Collections.singletonList(new FieldFormatterCleanup("title", new ProtectTermsFormatter(protectedTermsLoader)))));
+                Collections.singletonList(
+                        new FieldFormatterCleanup("title", new ProtectTermsFormatter(protectedTermsLoader)))));
         BibEntry entry = new BibEntry();
         entry.setField("title", "AlGaAs");
 
@@ -311,11 +312,11 @@ public void cleanupLatexMergesTwoLatexMathEnvironments() {
     public void convertToBiblatexMovesJournalToJournalTitle() {
         CleanupPreset preset = new CleanupPreset(CleanupPreset.CleanupStep.CONVERT_TO_BIBLATEX);
         BibEntry entry = new BibEntry();
-        entry.setField("journal", "test");
+        entry.setField(FieldName.JOURNAL, "test");
 
         worker.cleanup(preset, entry);
-        Assert.assertEquals(Optional.empty(), entry.getField("journal"));
-        Assert.assertEquals(Optional.of("test"), entry.getField("journaltitle"));
+        Assert.assertEquals(Optional.empty(), entry.getField(FieldName.JOURNAL));
+        Assert.assertEquals(Optional.of("test"), entry.getField(FieldName.JOURNALTITLE));
     }
 
     @Test