Quality check escaped ampersand

CHANGELOG.md

@@ -20,6 +20,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 - We added support for multiple languages for exporting to and importing references from MS Office. [#9699](https://github.com/JabRef/jabref/issues/9699)
 - We enabled scrolling in the groups list when dragging a group on another group. [#2869](https://github.com/JabRef/jabref/pull/2869)
 - We added the option to automatically download online files when a new entry is created from an existing ID (e.g. DOI). The option can be disabled in the preferences under "Import and Export" [#9756](https://github.com/JabRef/jabref/issues/9756)
+- We added a new Integrity check for unscaped ampersands. [koppor#585](https://github.com/koppor/jabref/issues/585)
 
 
 ### Changed

src/main/java/org/jabref/logic/integrity/AmpersandChecker.java

@@ -0,0 +1,41 @@
+package org.jabref.logic.integrity;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.MatchResult;
+import java.util.regex.Pattern;
+
+import org.jabref.logic.l10n.Localization;
+import org.jabref.model.entry.BibEntry;
+import org.jabref.model.entry.field.Field;
+
+import com.google.common.base.CharMatcher;
+
+/**
+ * Checks if the BibEntry contains unescaped ampersands.
+ */
+public class AmpersandChecker implements EntryChecker {
+    // matches for an & preceded by any number of \
+    private static final Pattern BACKSLASH_PRECEDED_AMPERSAND = Pattern.compile("\\\\*&");
+
+    @Override
+    public List<IntegrityMessage> check(BibEntry entry) {
+        List<IntegrityMessage> results = new ArrayList<>();
+
+        for (Map.Entry<Field, String> field : entry.getFieldMap().entrySet()) {
+            // counts the number of even \ occurrences preceding an &
+            long unescapedAmpersands = BACKSLASH_PRECEDED_AMPERSAND.matcher(field.getValue())
+                    .results()
+                    .map(MatchResult::group)
+                    .filter(m -> CharMatcher.is('\\').countIn(m) % 2 == 0)
+                    .count();
+
+            if (unescapedAmpersands > 0) {
+                results.add(new IntegrityMessage(Localization.lang("Found %0 unescaped '&'", unescapedAmpersands), entry, field.getKey()));
+                // note: when changing the message - also do so in tests
+            }
+        }
+        return results;
+    }
+}

src/main/java/org/jabref/logic/integrity/IntegrityCheck.java

@@ -37,8 +37,9 @@ public IntegrityCheck(BibDatabaseContext bibDatabaseContext,
                 new HTMLCharacterChecker(),
                 new EntryLinkChecker(bibDatabaseContext.getDatabase()),
                 new CitationKeyDeviationChecker(bibDatabaseContext, citationKeyPatternPreferences),
-                new CitationKeyDuplicationChecker(bibDatabaseContext.getDatabase())
-        ));
+                new CitationKeyDuplicationChecker(bibDatabaseContext.getDatabase()),
+                new AmpersandChecker()
+                ));
         if (bibDatabaseContext.isBiblatexMode()) {
             entryCheckers.addAll(List.of(
                     new JournalInAbbreviationListChecker(StandardField.JOURNALTITLE, journalAbbreviationRepository),

src/main/resources/l10n/JabRef_de.properties

@@ -1561,6 +1561,8 @@ Verse=Vers
 change\ entries\ of\ group=Ändere Einträge der Gruppe
 odd\ number\ of\ unescaped\ '\#'=Ungerade Anzahl an '\#' Maskierungszeichen
 
+Found\ %0\ unescaped\ '\&'=%0 unmaskierte(s) '&' gefunden
+
 Show\ diff=Zeige Änderungen
 Copy\ Version=Kopiere Version
 Maintainers=Maintainer

src/main/resources/l10n/JabRef_en.properties

@@ -1566,6 +1566,8 @@ Verse=Verse
 change\ entries\ of\ group=change entries of group
 odd\ number\ of\ unescaped\ '\#'=odd number of unescaped '#'
 
+Found\ %0\ unescaped\ '\&'=Found %0 unescaped '&'
+
 Show\ diff=Show diff
 Copy\ Version=Copy Version
 Maintainers=Maintainers

src/test/java/org/jabref/logic/integrity/AmpersandCheckerTest.java

@@ -0,0 +1,68 @@
+package org.jabref.logic.integrity;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.jabref.model.entry.BibEntry;
+import org.jabref.model.entry.field.Field;
+import org.jabref.model.entry.field.StandardField;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class AmpersandCheckerTest {
+
+    private final AmpersandChecker checker = new AmpersandChecker();
+    private final BibEntry entry = new BibEntry();
+
+    @ParameterizedTest
+    @MethodSource("provideAcceptedInputs")
+    void acceptsAllowedInputs(List<IntegrityMessage> expected, Field field, String value) {
+        entry.setField(field, value);
+        assertEquals(expected, checker.check(entry));
+    }
+
+    private static Stream<Arguments> provideAcceptedInputs() {
+        return Stream.of(
+                Arguments.of(Collections.emptyList(), StandardField.TITLE, "No ampersand at all"),
+                Arguments.of(Collections.emptyList(), StandardField.FOREWORD, "Properly escaped \\&"),
+                Arguments.of(Collections.emptyList(), StandardField.AUTHOR, "\\& Multiple properly escaped \\&"),
+                Arguments.of(Collections.emptyList(), StandardField.BOOKTITLE, "\\\\\\& With multiple backslashes"),
+                Arguments.of(Collections.emptyList(), StandardField.COMMENT, "\\\\\\& With multiple backslashes multiple times \\\\\\\\\\&"),
+                Arguments.of(Collections.emptyList(), StandardField.NOTE, "In the \\& middle of \\\\\\& something")
+        );
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideUnacceptedInputs")
+    void rejectsDisallowedInputs(String expectedMessage, Field field, String value) {
+        entry.setField(field, value);
+        assertEquals(List.of(new IntegrityMessage(expectedMessage, entry, field)), checker.check(entry));
+    }
+
+    private static Stream<Arguments> provideUnacceptedInputs() {
+        return Stream.of(
+                Arguments.of("Found 1 unescaped '&'", StandardField.SUBTITLE, "A single &"),
+                Arguments.of("Found 2 unescaped '&'", StandardField.ABSTRACT, "Multiple \\\\& not properly & escaped"),
+                Arguments.of("Found 1 unescaped '&'", StandardField.AUTHOR, "To many backslashes \\\\&"),
+                Arguments.of("Found 2 unescaped '&'", StandardField.LABEL, "\\\\\\\\& Multiple times \\\\& multiple backslashes")
+        );
+    }
+
+    @Test
+    void entryWithEscapedAndUnescapedAmpersand() {
+        entry.setField(StandardField.TITLE, "Jack \\& Jill & more");
+        assertEquals(List.of(new IntegrityMessage("Found 1 unescaped '&'", entry, StandardField.TITLE)), checker.check(entry));
+    }
+
+    @Test
+    void entryWithMultipleEscapedAndUnescapedAmpersands() {
+        entry.setField(StandardField.AFTERWORD, "May the force be with you & live long \\\\& prosper \\& to infinity \\\\\\& beyond & assemble \\\\\\\\& excelsior!");
+        assertEquals(List.of(new IntegrityMessage("Found 4 unescaped '&'", entry, StandardField.AFTERWORD)), checker.check(entry));
+    }
+}