Add a few cleanup formatters

src/main/java/net/sf/jabref/importer/HTMLConverter.java

@@ -15,6 +15,7 @@
  */
 package net.sf.jabref.importer;
 
+import java.util.Objects;
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -45,9 +46,7 @@ public HTMLConverter() {
     }
 
     public String formatUnicode(String text) {
-        if (text == null) {
-            return null;
-        }
+        Objects.requireNonNull(text);
 
         if (text.isEmpty()) {
             return text;
@@ -94,9 +93,7 @@ public String formatUnicode(String text) {
 
     @Override
     public String format(String text) {
-        if (text == null) {
-            return null;
-        }
+        Objects.requireNonNull(text);
 
         if (text.isEmpty()) {
             return text;

src/main/java/net/sf/jabref/logic/formatter/Formatter.java

@@ -13,22 +13,24 @@ public interface Formatter {
     /**
      * Returns a human readable name of the formatter usable for e.g. in the GUI
      *
-     * @return the name of the formatter
+     * @return the name of the formatter, always not null
      */
     String getName();
 
 
     /**
      * Returns a unique key for the formatter that can be used for its identification
-     * @return
+     * @return the key of the formatter, always not null
      */
     String getKey();
 
     /**
      * Formats a field value by with a particular formatter transformation.
      *
+     * Calling this method with a null argument results in a NullPointerException.
+     *
      * @param value the input String
-     * @return the formatted output String
+     * @return the formatted output String, always not null
      */
     String format(String value);
 }

src/main/java/net/sf/jabref/logic/formatter/IdentityFormatter.java

@@ -1,5 +1,7 @@
 package net.sf.jabref.logic.formatter;
 
+import java.util.Objects;
+
 /**
  * It may seem useless, but is needed as a fallback option
  */
@@ -17,6 +19,7 @@ public String getKey() {
 
     @Override
     public String format(String value) {
+        Objects.requireNonNull(value);
         return value;
     }
 }

src/main/java/net/sf/jabref/logic/formatter/bibtexfields/MonthFormatter.java

@@ -3,6 +3,8 @@
 import net.sf.jabref.logic.formatter.Formatter;
 import net.sf.jabref.model.entry.MonthUtil;
 
+import java.util.Objects;
+
 public class MonthFormatter implements Formatter {
 
     @Override
@@ -17,6 +19,7 @@ public String getKey() {
 
     @Override
     public String format(String value) {
+        Objects.requireNonNull(value);
         MonthUtil.Month month = MonthUtil.getMonth(value);
         if (month.isValid()) {
             return month.bibtexFormat;

src/main/java/net/sf/jabref/logic/formatter/bibtexfields/PageNumbersFormatter.java

@@ -2,6 +2,7 @@
 
 import net.sf.jabref.logic.formatter.Formatter;
 
+import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -48,9 +49,10 @@ public String getKey() {
      */
     @Override
     public String format(String value) {
+        Objects.requireNonNull(value);
 
-        // nothing to do
-        if ((value == null) || value.isEmpty()) {
+        if (value.isEmpty()) {
+            // nothing to do
             return value;
         }
 

src/main/java/net/sf/jabref/logic/formatter/bibtexfields/RemoveBracesFormatter.java

@@ -0,0 +1,62 @@
+package net.sf.jabref.logic.formatter.bibtexfields;
+
+import net.sf.jabref.logic.formatter.Formatter;
+
+import java.util.Objects;
+
+public class RemoveBracesFormatter implements Formatter {
+
+    @Override
+    public String getName() {
+        return "Remove enclosing double braces";
+    }
+
+    @Override
+    public String getKey() {
+        return "RemoveBracesFormatter";
+    }
+
+    @Override
+    public String format(String value) {
+        Objects.requireNonNull(value);
+
+        String formatted = value;
+        while (formatted.length() >= 2 && formatted.charAt(0) == '{' && formatted.charAt(formatted.length() - 1)
+                == '}') {
+            String trimmed = formatted.substring(1, formatted.length() - 1);
+
+            // It could be that the removed braces were not matching
+            // For example, "{A} test {B}" results in "A} test {B"
+            // In this case, trimmed has a closing } without an opening { before that
+            if(hasNegativeBraceCount(trimmed)) {
+                return formatted;
+            } else {
+                formatted = trimmed;
+            }
+        }
+        return formatted;
+    }
+
+    /**
+     * Check if a string at any point has had more ending } braces than opening { ones.
+     * Will e.g. return true for the string "DNA} blahblal {EPA"
+     *
+     * @param value The string to check.
+     * @return true if at any index the brace count is negative.
+     */
+    private boolean hasNegativeBraceCount(String value) {
+        int braceCount = 0;
+        for (int index = 0; index < value.length(); index++) {
+            char charAtIndex = value.charAt(index);
+            if (charAtIndex == '{') {
+                braceCount++;
+            } else if (charAtIndex == '}') {
+                braceCount--;
+            }
+            if (braceCount < 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+}

src/main/java/net/sf/jabref/logic/formatter/bibtexfields/SuperscriptFormatter.java

@@ -16,6 +16,8 @@
 package net.sf.jabref.logic.formatter.bibtexfields;
 
 import net.sf.jabref.logic.formatter.Formatter;
+
+import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -50,9 +52,10 @@ public String getKey() {
      */
     @Override
     public String format(String value) {
+        Objects.requireNonNull(value);
 
-        // nothing to do
-        if ((value == null) || value.isEmpty()) {
+        if (value.isEmpty()) {
+            // nothing to do
             return value;
         }
 

src/main/java/net/sf/jabref/logic/formatter/bibtexfields/TrimFormatter.java

@@ -0,0 +1,25 @@
+package net.sf.jabref.logic.formatter.bibtexfields;
+
+import net.sf.jabref.logic.formatter.Formatter;
+import net.sf.jabref.model.entry.MonthUtil;
+
+import java.util.Objects;
+
+public class TrimFormatter implements Formatter {
+
+    @Override
+    public String getName() {
+        return "Trim whitespace";
+    }
+
+    @Override
+    public String getKey() {
+        return "TrimFormatter";
+    }
+
+    @Override
+    public String format(String value) {
+        Objects.requireNonNull(value);
+        return value.trim();
+    }
+}

src/main/java/net/sf/jabref/logic/formatter/bibtexfields/UnitFormatter.java

@@ -16,6 +16,7 @@
 package net.sf.jabref.logic.formatter.bibtexfields;
 
 import java.util.Arrays;
+import java.util.Objects;
 
 import net.sf.jabref.logic.formatter.Formatter;
 import net.sf.jabref.logic.l10n.Localization;
@@ -129,7 +130,8 @@ private static String format(String text, String[] listOfWords) {
 
     @Override
     public String format(String text) {
-        if ((text == null) || text.isEmpty()) {
+        Objects.requireNonNull(text);
+        if (text.isEmpty()) {
             return text;
         }
         return format(text, UnitFormatter.UNIT_COMBINATIONS);

src/main/java/net/sf/jabref/logic/formatter/casechanger/CaseKeeper.java

@@ -16,6 +16,7 @@
 package net.sf.jabref.logic.formatter.casechanger;
 
 import java.util.Arrays;
+import java.util.Objects;
 
 import net.sf.jabref.logic.formatter.Formatter;
 import net.sf.jabref.logic.l10n.Localization;
@@ -35,7 +36,9 @@ private String format(String text, String[] listOfWords) {
 
     @Override
     public String format(String text) {
-        if ((text == null) || text.isEmpty()) {
+        Objects.requireNonNull(text);
+
+        if (text.isEmpty()) {
             return text;
         }
         final CaseKeeperList list = new CaseKeeperList();

src/main/java/net/sf/jabref/logic/formatter/minifier/AuthorsMinifier.java

@@ -2,6 +2,8 @@
 
 import net.sf.jabref.logic.formatter.Formatter;
 
+import java.util.Objects;
+
 /**
  * Replaces three or more authors with and others
  */
@@ -24,8 +26,10 @@ public String getKey() {
      */
     @Override
     public String format(String value) {
-        // nothing to do
-        if ((value == null) || value.isEmpty()) {
+        Objects.requireNonNull(value);
+
+        if (value.isEmpty()) {
+            // nothing to do
             return value;
         }
 

src/test/java/net/sf/jabref/importer/HTMLConverterTest.java

@@ -24,11 +24,6 @@ public void testBasic() {
         assertEquals("aaa", conv.formatUnicode("aaa"));
     }
 
-    @Test
-    public void testHTMLNull() {
-        assertEquals(null, conv.format(null));
-    }
-
     @Test
     public void testHTMLEmpty() {
         assertEquals("", conv.format(""));
@@ -72,9 +67,9 @@ public void testUnicodeSingle() {
         assertEquals("a", conv.formatUnicode("a"));
     }
 
-    @Test
+    @Test(expected = NullPointerException.class)
     public void testUnicodeNull() {
-        assertEquals(null, conv.formatUnicode(null));
+        conv.formatUnicode(null);
     }
 
     @Test

src/test/java/net/sf/jabref/logic/formatter/FormatterTest.java

@@ -0,0 +1,91 @@
+package net.sf.jabref.logic.formatter;
+
+import net.sf.jabref.Globals;
+import net.sf.jabref.JabRefPreferences;
+import net.sf.jabref.importer.HTMLConverter;
+import net.sf.jabref.logic.formatter.bibtexfields.*;
+import net.sf.jabref.logic.formatter.casechanger.*;
+import net.sf.jabref.logic.formatter.minifier.AuthorsMinifier;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+import static org.junit.Assert.*;
+
+@RunWith(Parameterized.class)
+public class FormatterTest {
+
+    @BeforeClass
+    public static void setUp() {
+        Globals.prefs = JabRefPreferences.getInstance();
+    }
+
+    @Test
+    public void getNameReturnsNotNull() {
+        assertNotNull(formatter.getName());
+    }
+
+    @Test
+    public void getNameReturnsNotEmpty() {
+        assertNotEquals("", formatter.getName());
+    }
+
+    @Test
+    public void getKeyReturnsNotNull() {
+        assertNotNull(formatter.getKey());
+    }
+
+    @Test
+    public void getKeyReturnsNotEmpty() {
+        assertNotEquals("", formatter.getKey());
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void formatOfNullThrowsException() {
+        formatter.format(null);
+    }
+
+    @Test
+    public void formatOfEmptyStringReturnsEmpty() {
+        assertEquals("", formatter.format(""));
+    }
+
+    @Test
+    public void formatNotReturnsNull() {
+        assertNotNull(formatter.format("string"));
+    }
+
+    public Formatter formatter;
+
+    public FormatterTest(Formatter formatter) {
+        this.formatter = formatter;
+    }
+
+    @Parameterized.Parameters(name = "{index}: {0}")
+    public static Collection<Object[]> instancesToTest() {
+        return Arrays.asList(
+                new Object[]{new AuthorsFormatter()},
+                new Object[]{new UpperEachFirstCaseChanger()},
+                new Object[]{new UpperCaseChanger()},
+                new Object[]{new MonthFormatter()},
+                new Object[]{new LatexFormatter()},
+                new Object[]{new IdentityFormatter()},
+                new Object[]{new UpperFirstCaseChanger()},
+                new Object[]{new AuthorsMinifier()},
+                new Object[]{new DateFormatter()},
+                new Object[]{new TitleCaseChanger()},
+                new Object[]{new CaseKeeper()},
+                new Object[]{new PageNumbersFormatter()},
+                new Object[]{new LowerCaseChanger()},
+                new Object[]{new TrimFormatter()},
+                new Object[]{new HTMLConverter()},
+                new Object[]{new SuperscriptFormatter()},
+                new Object[]{new UnitFormatter()},
+                new Object[]{new RemoveBracesFormatter()}
+        );
+    }
+}