Fix 2701 too may files found (#2732)

* Splitting up several variables for debugging.

* Checking if the 'database' value is not 'null' before invokig a method
-- this fixes incorrect match of multiple files caused by a (masked)
"null pointer exception".

* Restoring the previous (more compact) code style.

* Adding a unit test for the new fix.

* Removing unused member 'private String patternString'.

* Adding another test to MakeLabelWithoutDatabaseTest.java, to cover the
second 'if' branch in the 2701 fix.

* Removing parameter annotation comments from the tests in
MakeLabelWithoutDatabaseTest.java, since IntelliJ handles them
automagically.

* Removing unused commented-out class member.

src/main/java/org/jabref/logic/bibtexkeypattern/BibtexKeyPatternUtil.java

@@ -524,8 +524,13 @@ public static String makeLabel(BibEntry entry, String value, Character keywordDe
                  * form "pureauth..." which does not do this fallback
                  * substitution of editor.
                  */
-                String authString = entry.getField(FieldName.AUTHOR)
-                        .map(authorString -> normalize(database.resolveForStrings(authorString))).orElse("");
+                String authString;
+                if (database != null) {
+                    authString = entry.getField(FieldName.AUTHOR)
+                            .map(authorString -> normalize(database.resolveForStrings(authorString))).orElse("");
+                } else {
+                    authString = entry.getField(FieldName.AUTHOR).orElse("");
+                }
 
                 if (val.startsWith("pure")) {
                     // remove the "pure" prefix so the remaining
@@ -534,8 +539,12 @@ public static String makeLabel(BibEntry entry, String value, Character keywordDe
                 }
 
                 if (authString.isEmpty()) {
-                    authString = entry.getField(FieldName.EDITOR)
+                    if (database != null) {
+                        authString = entry.getField(FieldName.EDITOR)
                             .map(authorString -> normalize(database.resolveForStrings(authorString))).orElse("");
+                    } else {
+                        authString = entry.getField(FieldName.EDITOR).orElse("");
+                    }
                 }
 
                 // Gather all author-related checks, so we don't

src/test/java/org/jabref/logic/bibtexkeypattern/MakeLabelWithoutDatabaseTest.java

@@ -0,0 +1,41 @@
+package org.jabref.logic.bibtexkeypattern;
+
+import org.jabref.model.entry.BibEntry;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class MakeLabelWithoutDatabaseTest {
+
+    private BibEntry entry;
+
+    @Before
+    public void setUp() {
+        entry = new BibEntry();
+        entry.setField("author", "John Doe");
+        entry.setField("year", "2016");
+        entry.setField("title", "An awesome paper on JabRef");
+    }
+
+    @Test
+    public void makeLabelForFileSearch() {
+        String label =
+            BibtexKeyPatternUtil.makeLabel(entry, "auth", ',', null);
+        assertEquals("Doe", label);
+    }
+
+    @Test
+    public void makeEditorLabelForFileSearch() {
+        BibEntry localEntry = new BibEntry();
+        localEntry.setField("editor", "John Doe");
+        localEntry.setField("year", "2016");
+        localEntry.setField("title", "An awesome paper on JabRef");
+
+        String label =
+            BibtexKeyPatternUtil.makeLabel(localEntry, "auth", ',', null);
+        assertEquals("Doe", label);
+    }
+
+}