Fix search test NPE

src/main/java/org/jabref/gui/LibraryTab.java

@@ -316,7 +316,7 @@ private void onDatabaseLoadingSucceed(ParserResult result) {
     }
 
     public void createLuceneManager() {
-        luceneManager = new LuceneManager(bibDatabaseContext, taskExecutor, preferencesService.getFilePreferences());
+        luceneManager = new LuceneManager(bibDatabaseContext, taskExecutor, preferencesService.getFilePreferences(), false);
         stateManager.setLuceneManager(bibDatabaseContext, luceneManager);
     }
 

src/main/java/org/jabref/logic/search/DatabaseSearcher.java

@@ -26,7 +26,7 @@ public class DatabaseSearcher {
     public DatabaseSearcher(SearchQuery query, BibDatabaseContext databaseContext, TaskExecutor taskExecutor, FilePreferences filePreferences) throws IOException {
         this.databaseContext = databaseContext;
         this.query = Objects.requireNonNull(query);
-        this.luceneManager = new LuceneManager(databaseContext, taskExecutor, filePreferences);
+        this.luceneManager = new LuceneManager(databaseContext, taskExecutor, filePreferences, true);
     }
 
     /**
@@ -37,6 +37,7 @@ public List<BibEntry> getMatches() {
 
         if (!query.isValid()) {
             LOGGER.warn("Search failed: invalid search expression");
+            luceneManager.close();
             return Collections.emptyList();
         }
         List<BibEntry> matchEntries = luceneManager.search(query)

src/main/java/org/jabref/logic/search/LuceneManager.java

@@ -39,21 +39,21 @@ public class LuceneManager {
     private final LuceneIndexer linkedFilesIndexer;
     private final LuceneSearcher luceneSearcher;
 
-    public LuceneManager(BibDatabaseContext databaseContext, TaskExecutor executor, FilePreferences preferences) {
+    public LuceneManager(BibDatabaseContext databaseContext, TaskExecutor executor, FilePreferences preferences, boolean waitOnClose) {
         this.taskExecutor = executor;
         this.databaseContext = databaseContext;
         this.shouldIndexLinkedFiles = preferences.fulltextIndexLinkedFilesProperty();
         this.preferencesListener = (observable, oldValue, newValue) -> bindToPreferences(newValue);
         this.shouldIndexLinkedFiles.addListener(preferencesListener);
 
-        this.bibFieldsIndexer = new BibFieldsIndexer(databaseContext);
+        this.bibFieldsIndexer = new BibFieldsIndexer(databaseContext, waitOnClose);
 
         LuceneIndexer indexer;
         try {
-            indexer = new DefaultLinkedFilesIndexer(databaseContext, preferences);
+            indexer = new DefaultLinkedFilesIndexer(databaseContext, preferences, waitOnClose);
         } catch (IOException e) {
             LOGGER.debug("Error initializing linked files index - using read only index");
-            indexer = new ReadOnlyLinkedFilesIndexer(databaseContext);
+            indexer = new ReadOnlyLinkedFilesIndexer(databaseContext, waitOnClose);
         }
         linkedFilesIndexer = indexer;
 

src/main/java/org/jabref/logic/search/indexing/BibFieldsIndexer.java

@@ -29,13 +29,15 @@
 public class BibFieldsIndexer implements LuceneIndexer {
     private static final Logger LOGGER = LoggerFactory.getLogger(BibFieldsIndexer.class);
     private final BibDatabaseContext databaseContext;
+    private final boolean waitOnClose;
     private final String libraryName;
     private final Directory indexDirectory;
     private IndexWriter indexWriter;
     private SearcherManager searcherManager;
 
-    public BibFieldsIndexer(BibDatabaseContext databaseContext) {
+    public BibFieldsIndexer(BibDatabaseContext databaseContext, boolean waitOnClose) {
         this.databaseContext = databaseContext;
+        this.waitOnClose = waitOnClose;
         this.libraryName = databaseContext.getDatabasePath().map(path -> path.getFileName().toString()).orElseGet(() -> "unsaved");
 
         IndexWriterConfig config = new IndexWriterConfig(SearchFieldConstants.LATEX_AWARE_NGRAM_ANALYZER);
@@ -153,7 +155,11 @@ public SearcherManager getSearcherManager() {
 
     @Override
     public void close() {
-        HeadlessExecutorService.INSTANCE.execute(this::closeIndex);
+        if (waitOnClose) {
+            HeadlessExecutorService.INSTANCE.executeAndWait(this::closeIndex);
+        } else {
+            HeadlessExecutorService.INSTANCE.execute(this::closeIndex);
+        }
     }
 
     private void closeIndex() {

src/main/java/org/jabref/logic/search/indexing/DefaultLinkedFilesIndexer.java

@@ -51,16 +51,18 @@ public class DefaultLinkedFilesIndexer implements LuceneIndexer {
 
     private final BibDatabaseContext databaseContext;
     private final FilePreferences filePreferences;
+    private final boolean waitOnClose;
     private final String libraryName;
     private final Directory indexDirectory;
     private final IndexWriter indexWriter;
     private final SearcherManager searcherManager;
     private Path indexDirectoryPath;
     private Map<String, Long> indexedFiles;
 
-    public DefaultLinkedFilesIndexer(BibDatabaseContext databaseContext, FilePreferences filePreferences) throws IOException {
+    public DefaultLinkedFilesIndexer(BibDatabaseContext databaseContext, FilePreferences filePreferences, boolean waitOnClose) throws IOException {
         this.databaseContext = databaseContext;
         this.filePreferences = filePreferences;
+        this.waitOnClose = waitOnClose;
         this.libraryName = databaseContext.getDatabasePath().map(path -> path.getFileName().toString()).orElseGet(() -> "untitled");
         this.indexedFiles = new ConcurrentHashMap<>();
 
@@ -312,7 +314,11 @@ public SearcherManager getSearcherManager() {
 
     @Override
     public void close() {
-        HeadlessExecutorService.INSTANCE.execute(this::closeIndex);
+        if (waitOnClose) {
+            HeadlessExecutorService.INSTANCE.executeAndWait(this::closeIndex);
+        } else {
+            HeadlessExecutorService.INSTANCE.execute(this::closeIndex);
+        }
     }
 
     private void closeIndex() {

src/main/java/org/jabref/logic/search/indexing/ReadOnlyLinkedFilesIndexer.java

@@ -17,10 +17,12 @@
 
 public class ReadOnlyLinkedFilesIndexer implements LuceneIndexer {
     private static final Logger LOGGER = LoggerFactory.getLogger(ReadOnlyLinkedFilesIndexer.class);
+    private final boolean waitOnClose;
     private Directory indexDirectory;
     private SearcherManager searcherManager;
 
-    public ReadOnlyLinkedFilesIndexer(BibDatabaseContext databaseContext) {
+    public ReadOnlyLinkedFilesIndexer(BibDatabaseContext databaseContext, boolean waitOnClose) {
+        this.waitOnClose = waitOnClose;
         try {
             indexDirectory = FSDirectory.open(databaseContext.getFulltextIndexPath());
             searcherManager = new SearcherManager(indexDirectory, null);
@@ -60,7 +62,11 @@ public SearcherManager getSearcherManager() {
 
     @Override
     public void close() {
-        HeadlessExecutorService.INSTANCE.execute(this::closeIndex);
+        if (waitOnClose) {
+            HeadlessExecutorService.INSTANCE.executeAndWait(this::closeIndex);
+        } else {
+            HeadlessExecutorService.INSTANCE.execute(this::closeIndex);
+        }
     }
 
     private void closeIndex() {

src/test/java/org/jabref/logic/search/DatabaseSearcherTest.java

@@ -1,6 +1,7 @@
 package org.jabref.logic.search;
 
 import java.io.IOException;
+import java.nio.file.Path;
 import java.util.EnumSet;
 import java.util.List;
 import java.util.stream.Stream;
@@ -18,24 +19,29 @@
 import org.jabref.preferences.FilePreferences;
 
 import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.io.TempDir;
 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;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.when;
 
 public class DatabaseSearcherTest {
     private static final TaskExecutor TASK_EXECUTOR = new CurrentThreadTaskExecutor();
     private BibDatabaseContext databaseContext;
     private final FilePreferences filePreferences = mock(FilePreferences.class);
+    @TempDir
+    private Path indexDir;
 
     @BeforeEach
     void setUp() {
         when(filePreferences.shouldFulltextIndexLinkedFiles()).thenReturn(false);
         when(filePreferences.fulltextIndexLinkedFilesProperty()).thenReturn(mock(BooleanProperty.class));
-        databaseContext = new BibDatabaseContext();
+        databaseContext = spy(new BibDatabaseContext());
+        when(databaseContext.getFulltextIndexPath()).thenReturn(indexDir);
     }
 
     @ParameterizedTest

src/test/java/org/jabref/logic/search/DatabaseSearcherWithBibFilesTest.java

@@ -33,6 +33,7 @@
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.when;
 
 class DatabaseSearcherWithBibFilesTest {
@@ -77,7 +78,8 @@ private BibDatabaseContext initializeDatabaseFromPath(String testFile) throws Ex
 
     private BibDatabaseContext initializeDatabaseFromPath(Path testFile) throws Exception {
         ParserResult result = new BibtexImporter(mock(ImportFormatPreferences.class, Answers.RETURNS_DEEP_STUBS), new DummyFileUpdateMonitor()).importDatabase(testFile);
-        BibDatabaseContext databaseContext = result.getDatabaseContext();
+        BibDatabaseContext databaseContext = spy(result.getDatabaseContext());
+        when(databaseContext.getFulltextIndexPath()).thenReturn(indexDir);
 
         when(filePreferences.shouldFulltextIndexLinkedFiles()).thenReturn(true);
         when(filePreferences.fulltextIndexLinkedFilesProperty()).thenReturn(new SimpleBooleanProperty(true));

src/test/java/org/jabref/logic/search/indexing/LinkedFilesIndexerTest.java

@@ -42,7 +42,7 @@ void setUp(@TempDir Path indexDir) throws IOException {
         when(context.getFileDirectories(Mockito.any())).thenReturn(Collections.singletonList(Path.of("src/test/resources/pdfs")));
         when(context.getFulltextIndexPath()).thenReturn(indexDir);
 
-        this.indexer = new DefaultLinkedFilesIndexer(context, filePreferences);
+        this.indexer = new DefaultLinkedFilesIndexer(context, filePreferences, true);
     }
 
     @Test