diff --git a/app/src/main/java/foundation/e/drive/database/DbHelper.java b/app/src/main/java/foundation/e/drive/database/DbHelper.java
index 12828f24b6e787ef5934c8f0d209ffe3fcddaf8f..edc336bbec9145de6a99f0787fb98a7c5afd5988 100644
--- a/app/src/main/java/foundation/e/drive/database/DbHelper.java
+++ b/app/src/main/java/foundation/e/drive/database/DbHelper.java
@@ -14,6 +14,8 @@ import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteException;
 import android.database.sqlite.SQLiteOpenHelper;
 
+import androidx.annotation.VisibleForTesting;
+
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
@@ -84,8 +86,8 @@ public final class DbHelper extends SQLiteOpenHelper {
         }
     }
 
-
-    private static SyncedFileStateDAO openSyncedFileStateDAO(Context context, boolean writeMod){
+    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+    public static SyncedFileStateDAO openSyncedFileStateDAO(Context context, boolean writeMod) {
         final SyncedFileStateDAO dao = new SyncedFileStateDAO(context);
         try {
             dao.open(writeMod);
@@ -162,7 +164,7 @@ public final class DbHelper extends SQLiteOpenHelper {
         if (dao == null) {
             return new ArrayList<>();
         }
-        final List<SyncedFileState> result = dao.getBySyncedFolderID(ids);
+        final List<SyncedFileState> result = dao.getBySyncedFolderIds(ids);
         dao.close();
         return result;
     }
diff --git a/app/src/main/java/foundation/e/drive/database/SyncedFileStateDAO.java b/app/src/main/java/foundation/e/drive/database/SyncedFileStateDAO.java
index ee507044d064c247b857f6dc70b70f700b87609c..18cff0df548c69b8fb99787783f5a4463c431024 100644
--- a/app/src/main/java/foundation/e/drive/database/SyncedFileStateDAO.java
+++ b/app/src/main/java/foundation/e/drive/database/SyncedFileStateDAO.java
@@ -186,11 +186,17 @@ import static foundation.e.drive.database.SyncedFileStateContract.SYNCEDFOLDER_I
     }
 
     /**
-    * Fetch many SyncedFileState by their syncedFolder's id
-    * @param syncedFolderIds List<Long> of id of parent syncedFolder.
-    * @return List<SyncedFileState> List of SyncedFileState filtered on syncedFolder ID.
-    */
-    /* package */ List<SyncedFileState> getBySyncedFolderID(List<Long> syncedFolderIds) {
+     * Fetch every syncedFileState for subfile of directories identified by syncedFolder's id.
+     *
+     * @param syncedFolderIds List<Long> of SyncedFolderIds
+     * @return List<SyncedFileState> List of SyncedFileState filtered on syncedFolder ID. The result is an empty list
+     * if list of syncedFolderIds is null or empty
+     */
+    /* package */ List<SyncedFileState> getBySyncedFolderIds(List<Long> syncedFolderIds) {
+        final List<SyncedFileState> result = new ArrayList<>();
+        if (syncedFolderIds == null || syncedFolderIds.isEmpty()) {
+            return result;
+        }
         final String whereClause = SYNCEDFOLDER_ID + " IN (?)";
         final String[] whereValue = new String[] {
              syncedFolderIds.toString()
@@ -198,9 +204,7 @@ import static foundation.e.drive.database.SyncedFileStateContract.SYNCEDFOLDER_I
                 .replace("]", ")") };
 
         final Cursor cursor = mDB.query(TABLE_NAME, allColumns, whereClause, whereValue, null, null, null);
-
         cursor.moveToFirst();
-        final List<SyncedFileState> result = new ArrayList<>();
         while(!cursor.isAfterLast() ) {
             result.add( cursorToSyncedFileState(cursor) );
             cursor.moveToNext();
diff --git a/app/src/test/java/foundation/e/drive/database/SyncedFileStateDAOTest.java b/app/src/test/java/foundation/e/drive/database/SyncedFileStateDAOTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..945b8694edbeba55c7049a3b2e3983b04c9e0b56
--- /dev/null
+++ b/app/src/test/java/foundation/e/drive/database/SyncedFileStateDAOTest.java
@@ -0,0 +1,81 @@
+/*
+ * Copyright © MURENA SAS 2022.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package foundation.e.drive.database;
+
+import android.content.Context;
+import android.os.Build;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Ignore;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import foundation.e.drive.models.SyncedFileState;
+import foundation.e.drive.models.SyncedFolder;
+
+/**
+ * @author vincent Bourgmayer
+ */
+@RunWith(RobolectricTestRunner.class)
+@Config(sdk = Build.VERSION_CODES.O, manifest = Config.NONE)
+public class SyncedFileStateDAOTest {
+
+    private SyncedFileStateDAO daoUnderTest;
+    private final Context context;
+
+    public SyncedFileStateDAOTest() {
+        context = ApplicationProvider.getApplicationContext();
+    }
+
+
+    @Before
+    public void prepareDB() {
+        final SyncedFolder dummyFolder = new SyncedFolder("Picture", "local/", "remote/", true, true, true, true);
+        dummyFolder.setId(12);
+        DbHelper.insertSyncedFolder(dummyFolder, context);
+
+        final SyncedFileState dummy = new SyncedFileState(6, "foo.jpg", "local/foo.jpg", "remote/foo.jpg", "7777", 0L, 12, true, 3);
+        DbHelper.manageSyncedFileStateDB(dummy, "INSERT", context);
+
+        daoUnderTest = DbHelper.openSyncedFileStateDAO(context, false);
+    }
+
+    @After
+    public void closeDB() {
+        daoUnderTest.close();
+    }
+
+    @Test
+    public void getBySyncedFolderIds_emptyIdList_returnEmptyList() {
+        final List<Long> folderIds = new ArrayList<>();
+        final List<SyncedFileState> result = daoUnderTest.getBySyncedFolderIds(folderIds);
+        Assert.assertTrue(result.isEmpty());
+    }
+
+    /*
+     * @todo find why this test fails
+     */
+    @Test
+    @Ignore
+    public void getBySyncedFolderIds_notEmpty_returnOneFileState() {
+        final List<Long> folderIds = new ArrayList<>();
+        folderIds.add(new Long(12));
+        final List<SyncedFileState> result = daoUnderTest.getBySyncedFolderIds(folderIds);
+        Assert.assertFalse("result should contain 1 SyncedFileState but was empty", result.isEmpty());
+    }
+}