diff --git a/CMakeLists.txt b/CMakeLists.txt
index 50e9be8..28a8c0c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -90,3 +90,88 @@ target_include_directories(wino-mail-qt PRIVATE ${GMIME_INCLUDE_DIRS})
 
 # Install (optional)
 install(TARGETS wino-mail-qt DESTINATION bin)
+
+# Enable testing
+enable_testing()
+
+# Find Qt Test
+find_package(Qt6 COMPONENTS Test REQUIRED)
+
+# Unit tests for DAOs
+add_executable(tests_dao_unit
+    tests/unit/test_accountdao.cpp
+    tests/unit/test_folderdao.cpp
+    tests/unit/test_mailitemdao.cpp
+)
+
+target_link_libraries(tests_dao_unit
+    PRIVATE Qt6::Core Qt6::Test
+)
+
+if(USE_DTKWIDGET AND DTKWIDGET_FOUND)
+    target_link_libraries(tests_dao_unit PRIVATE ${DTKWIDGET_LIBS})
+endif()
+if(GMIME_FOUND)
+    target_link_libraries(tests_dao_unit PRIVATE ${GMIME_LIBRARIES})
+    target_include_directories(tests_dao_unit PRIVATE ${GMIME_INCLUDE_DIRS})
+endif()
+
+add_test(NAME dao_unit COMMAND tests_dao_unit)
+
+# Unit tests for Translator
+add_executable(tests_translator_unit
+    tests/unit/test_translator.cpp
+)
+
+target_link_libraries(tests_translator_unit
+    PRIVATE Qt6::Core Qt6::Test
+)
+
+if(USE_DTKWIDGET AND DTKWIDGET_FOUND)
+    target_link_libraries(tests_translator_unit PRIVATE ${DTKWIDGET_LIBS})
+endif()
+if(GMIME_FOUND)
+    target_link_libraries(tests_translator_unit PRIVATE ${GMIME_LIBRARIES})
+    target_include_directories(tests_translator_unit PRIVATE ${GMIME_INCLUDE_DIRS})
+endif()
+
+add_test(NAME translator_unit COMMAND tests_translator_unit)
+
+# Unit tests for EventBus
+add_executable(tests_eventbus_unit
+    tests/unit/test_eventbus.cpp
+)
+
+target_link_libraries(tests_eventbus_unit
+    PRIVATE Qt6::Core Qt6::Test
+)
+
+if(USE_DTKWIDGET AND DTKWIDGET_FOUND)
+    target_link_libraries(tests_eventbus_unit PRIVATE ${DTKWIDGET_LIBS})
+endif()
+if(GMIME_FOUND)
+    target_link_libraries(tests_eventbus_unit PRIVATE ${GMIME_LIBRARIES})
+    target_include_directories(tests_eventbus_unit PRIVATE ${GMIME_INCLUDE_DIRS})
+endif()
+
+add_test(NAME eventbus_unit COMMAND tests_eventbus_unit)
+
+# Integration tests (require full application context)
+add_executable(tests_sync_integration
+    tests/integration/test_syncscheduler.cpp
+    tests/integration/test_notificationmanager.cpp
+)
+
+target_link_libraries(tests_sync_integration
+    PRIVATE Qt6::Core Qt6::Gui Qt6::Widgets Qt6::Network Qt6::Sql Qt6::Test
+)
+
+if(USE_DTKWIDGET AND DTKWIDGET_FOUND)
+    target_link_libraries(tests_sync_integration PRIVATE ${DTKWIDGET_LIBS})
+endif()
+if(GMIME_FOUND)
+    target_link_libraries(tests_sync_integration PRIVATE ${GMIME_LIBRARIES})
+    target_include_directories(tests_sync_integration PRIVATE ${GMIME_INCLUDE_DIRS})
+endif()
+
+add_test(NAME sync_integration COMMAND tests_sync_integration)
diff --git a/tests/integration/test_notificationmanager.cpp b/tests/integration/test_notificationmanager.cpp
new file mode 100644
index 0000000..e69de29
diff --git a/tests/integration/test_syncscheduler.cpp b/tests/integration/test_syncscheduler.cpp
new file mode 100644
index 0000000..2a2ed40
--- /dev/null
+++ b/tests/integration/test_syncscheduler.cpp
@@ -0,0 +1,20 @@
+#include <QtTest/QtTest>
+#include "../../src/syncscheduler.h"
+
+class TestSyncScheduler : public QObject
+{
+    Q_OBJECT
+private slots:
+    void testShouldRunSync();
+};
+
+void TestSyncScheduler::testShouldRunSync()
+{
+    SyncScheduler scheduler;
+    // This test would need to mock QSettings and QDateTime
+    // For now, we just verify the object can be created
+    QVERIFY(true);
+}
+
+QTEST_MAIN(TestSyncScheduler)
+#include "test_syncscheduler.moc"
diff --git a/tests/unit/test_accountdao.cpp b/tests/unit/test_accountdao.cpp
new file mode 100644
index 0000000..3f4d354
--- /dev/null
+++ b/tests/unit/test_accountdao.cpp
@@ -0,0 +1,106 @@
+#include <QtTest/QtTest>
+#include "../../src/db/dao/accountdao.h"
+#include "../../src/db/databasemanager.h"
+#include "../../src/core/models/account.h"
+
+class TestAccountDao : public QObject
+{
+    Q_OBJECT
+private slots:
+    void initTestCase();
+    void cleanupTestCase();
+    void testInsertAndFind();
+    void testUpdate();
+    void testRemove();
+};
+
+void TestAccountDao::initTestCase()
+{
+    DatabaseManager::instance().openDatabase(":memory:");
+    DatabaseManager::instance().createTables();
+}
+
+void TestAccountDao::cleanupTestCase()
+{
+    DatabaseManager::instance().closeDatabase();
+}
+
+void TestAccountDao::testInsertAndFind()
+{
+    Account account;
+    account.setEmail("test@example.com");
+    account.setProvider("IMAP");
+    account.setHost("imap.example.com");
+    account.setPort(993);
+    account.setUsername("testuser");
+    account.setPassword("testpass");
+    account.setUseSsl(true);
+
+    bool inserted = AccountDao::insert(account);
+    QVERIFY(inserted);
+    QVERIFY(account.id() > 0);
+
+    Account found = AccountDao::findById(account.id());
+    QVERIFY(found.isValid());
+    QCOMPARE(found.email(), QString("test@example.com"));
+    QCOMPARE(found.provider(), QString("IMAP"));
+    QCOMPARE(found.host(), QString("imap.example.com"));
+    QCOMPARE(found.port(), 993);
+    QCOMPARE(found.username(), QString("testuser"));
+    QCOMPARE(found.password(), QString("testpass"));
+    QVERIFY(found.useSsl());
+}
+
+void TestAccountDao::testUpdate()
+{
+    Account account;
+    account.setEmail("original@example.com");
+    account.setProvider("IMAP");
+    account.setHost("imap.example.com");
+    account.setPort(993);
+    account.setUsername("user");
+    account.setPassword("pass");
+    account.setUseSsl(true);
+
+    bool inserted = AccountDao::insert(account);
+    QVERIFY(inserted);
+    qint64 id = account.id();
+
+    account.setEmail("updated@example.com");
+    account.setProvider("Gmail");
+    account.setUseSsl(false);
+
+    bool updated = AccountDao::update(account);
+    QVERIFY(updated);
+
+    Account found = AccountDao::findById(id);
+    QVERIFY(found.isValid());
+    QCOMPARE(found.email(), QString("updated@example.com"));
+    QCOMPARE(found.provider(), QString("Gmail"));
+    QVERIFY(!found.useSsl());
+}
+
+void TestAccountDao::testRemove()
+{
+    Account account;
+    account.setEmail("todelete@example.com");
+    account.setProvider("IMAP");
+    account.setHost("imap.example.com");
+    account.setPort(993);
+    account.setUsername("user");
+    account.setPassword("pass");
+    account.setUseSsl(true);
+
+    bool inserted = AccountDao::insert(account);
+    QVERIFY(inserted);
+    qint64 id = account.id();
+
+    bool removed = AccountDao::remove(id);
+    QVERIFY(removed);
+
+    Account found = AccountDao::findById(id);
+    QVERIFY(!found.isValid());
+}
+
+QTEST_MAIN(TestAccountDao)
+#include "test_accountdao.moc"
diff --git a/tests/unit/test_eventbus.cpp b/tests/unit/test_eventbus.cpp
new file mode 100644
index 0000000..225173c
--- /dev/null
+++ b/tests/unit/test_eventbus.cpp
@@ -0,0 +1,34 @@
+#include <QtTest/QtTest>
+#include "../../src/core/eventbus.h"
+#include "../../src/core/events.h"
+
+class TestEventBus : public QObject
+{
+    Q_OBJECT
+private slots:
+    void testPublishAndSubscribe();
+};
+
+void TestEventBus::testPublishAndSubscribe()
+{
+    bool received = false;
+    int value = 0;
+
+    // Subscribe to an event of type int
+    auto subscription = EventBus::instance().subscribe<int>([&](int data) {
+        received = true;
+        value = data;
+    });
+
+    // Publish an event
+    EventBus::instance().publish<int>(42);
+
+    // Check that we received the event
+    QVERIFY(received);
+    QCOMPARE(value, 42);
+
+    // Unsubscribe (optional, subscription goes out of scope)
+}
+
+QTEST_MAIN(TestEventBus)
+#include "test_eventbus.moc"
diff --git a/tests/unit/test_folderdao.cpp b/tests/unit/test_folderdao.cpp
new file mode 100644
index 0000000..6c7ebd1
--- /dev/null
+++ b/tests/unit/test_folderdao.cpp
@@ -0,0 +1,92 @@
+#include <QtTest/QtTest>
+#include "../../src/db/dao/folderdao.h"
+#include "../../src/db/databasemanager.h"
+#include "../../src/core/models/folder.h"
+
+class TestFolderDao : public QObject
+{
+    Q_OBJECT
+private slots:
+    void initTestCase();
+    void cleanupTestCase();
+    void testInsertAndFind();
+    void testUpdate();
+    void testRemove();
+};
+
+void TestFolderDao::initTestCase()
+{
+    DatabaseManager::instance().openDatabase(":memory:");
+    DatabaseManager::instance().createTables();
+}
+
+void TestFolderDao::cleanupTestCase()
+{
+    DatabaseManager::instance().closeDatabase();
+}
+
+void TestFolderDao::testInsertAndFind()
+{
+    Folder folder;
+    folder.setAccountId(1);
+    folder.setName("Inbox");
+    folder.setPath("INBOX");
+    folder.setIsInbox(true);
+
+    bool inserted = FolderDao::insert(folder);
+    QVERIFY(inserted);
+    QVERIFY(folder.id() > 0);
+
+    Folder found = FolderDao::findById(folder.id());
+    QVERIFY(found.isValid());
+    QCOMPARE(found.accountId(), 1);
+    QCOMPARE(found.name(), QString("Inbox"));
+    QCOMPARE(found.path(), QString("INBOX"));
+    QVERIFY(found.isInbox());
+}
+
+void TestFolderDao::testUpdate()
+{
+    Folder folder;
+    folder.setAccountId(1);
+    folder.setName("Drafts");
+    folder.setPath("Drafts");
+    folder.setIsInbox(false);
+
+    bool inserted = FolderDao::insert(folder);
+    QVERIFY(inserted);
+    qint64 id = folder.id();
+
+    folder.setName("Updated Drafts");
+    folder.setPath("Updated/Drafts");
+
+    bool updated = FolderDao::update(folder);
+    QVERIFY(updated);
+
+    Folder found = FolderDao::findById(id);
+    QVERIFY(found.isValid());
+    QCOMPARE(found.name(), QString("Updated Drafts"));
+    QCOMPARE(found.path(), QString("Updated/Drafts"));
+}
+
+void TestFolderDao::testRemove()
+{
+    Folder folder;
+    folder.setAccountId(1);
+    folder.setName("ToDelete");
+    folder.setPath("ToDelete");
+    folder.setIsInbox(false);
+
+    bool inserted = FolderDao::insert(folder);
+    QVERIFY(inserted);
+    qint64 id = folder.id();
+
+    bool removed = FolderDao::remove(id);
+    QVERIFY(removed);
+
+    Folder found = FolderDao::findById(id);
+    QVERIFY(!found.isValid());
+}
+
+QTEST_MAIN(TestFolderDao)
+#include "test_folderdao.moc"
diff --git a/tests/unit/test_mailitemdao.cpp b/tests/unit/test_mailitemdao.cpp
new file mode 100644
index 0000000..f82cf7f
--- /dev/null
+++ b/tests/unit/test_mailitemdao.cpp
@@ -0,0 +1,128 @@
+#include <QtTest/QtTest>
+#include "../../src/db/dao/mailitemdao.h"
+#include "../../src/db/databasemanager.h"
+#include "../../src/core/models/mailitem.h"
+#include "../../src/core/models/account.h"
+#include "../../src/core/models/folder.h"
+
+class TestMailItemDao : public QObject
+{
+    Q_OBJECT
+private slots:
+    void initTestCase();
+    void cleanupTestCase();
+    void testInsertAndFind();
+    void testUpdate();
+    void testRemove();
+};
+
+void TestMailItemDao::initTestCase()
+{
+    DatabaseManager::instance().openDatabase(":memory:");
+    DatabaseManager::instance().createTables();
+    // We need an account and folder for the mailitem
+    Account account;
+    account.setEmail("test@example.com");
+    account.setProvider("IMAP");
+    account.setHost("imap.example.com");
+    account.setPort(993);
+    account.setUsername("testuser");
+    account.setPassword("testpass");
+    account.setUseSsl(true);
+    bool accountInserted = AccountDao::insert(account);
+    QVERIFY(accountInserted);
+
+    Folder folder;
+    folder.setAccountId(account.id());
+    folder.setName("Inbox");
+    folder.setPath("INBOX");
+    folder.setIsInbox(true);
+    bool folderInserted = FolderDao::insert(folder);
+    QVERIFY(folderInserted);
+}
+
+void TestMailItemDao::cleanupTestCase()
+{
+    DatabaseManager::instance().closeDatabase();
+}
+
+void TestMailItemDao::testInsertAndFind()
+{
+    MailItem item;
+    item.setAccountId(1); // from account inserted in init
+    item.setFolderId(1);  // from folder inserted in init
+    item.setSubject("Test Subject");
+    item.setFrom("sender@example.com");
+    item.setTo("receiver@example.com");
+    item.setDate(QDateTime::currentDateTimeUtc());
+    item.setContent("Test content");
+    item.setUid("12345");
+
+    bool inserted = MailItemDao::insert(item);
+    QVERIFY(inserted);
+    QVERIFY(item.id() > 0);
+
+    MailItem found = MailItemDao::findById(item.id());
+    QVERIFY(found.isValid());
+    QCOMPARE(found.accountId(), 1);
+    QCOMPARE(found.folderId(), 1);
+    QCOMPARE(found.subject(), QString("Test Subject"));
+    QCOMPARE(found.from(), QString("sender@example.com"));
+    QCOMPARE(found.to(), QString("receiver@example.com"));
+    QCOMPARE(found.content(), QString("Test content"));
+    QCOMPARE(found.uid(), QString("12345"));
+}
+
+void TestMailItemDao::testUpdate()
+{
+    MailItem item;
+    item.setAccountId(1);
+    item.setFolderId(1);
+    item.setSubject("Original Subject");
+    item.setFrom("sender@example.com");
+    item.setTo("receiver@example.com");
+    item.setDate(QDateTime::currentDateTimeUtc());
+    item.setContent("Original content");
+    item.setUid("12345");
+
+    bool inserted = MailItemDao::insert(item);
+    QVERIFY(inserted);
+    qint64 id = item.id();
+
+    item.setSubject("Updated Subject");
+    item.setContent("Updated content");
+
+    bool updated = MailItemDao::update(item);
+    QVERIFY(updated);
+
+    MailItem found = MailItemDao::findById(id);
+    QVERIFY(found.isValid());
+    QCOMPARE(found.subject(), QString("Updated Subject"));
+    QCOMPARE(found.content(), QString("Updated content"));
+}
+
+void TestMailItemDao::testRemove()
+{
+    MailItem item;
+    item.setAccountId(1);
+    item.setFolderId(1);
+    item.setSubject("To Delete");
+    item.setFrom("sender@example.com");
+    item.setTo("receiver@example.com");
+    item.setDate(QDateTime::currentDateTimeUtc());
+    item.setContent("To be deleted");
+    item.setUid("12345");
+
+    bool inserted = MailItemDao::insert(item);
+    QVERIFY(inserted);
+    qint64 id = item.id();
+
+    bool removed = MailItemDao::remove(id);
+    QVERIFY(removed);
+
+    MailItem found = MailItemDao::findById(id);
+    QVERIFY(!found.isValid());
+}
+
+QTEST_MAIN(TestMailItemDao)
+#include "test_mailitemdao.moc"
diff --git a/tests/unit/test_translator.cpp b/tests/unit/test_translator.cpp
new file mode 100644
index 0000000..def797e
--- /dev/null
+++ b/tests/unit/test_translator.cpp
@@ -0,0 +1,47 @@
+#include <QtTest/QtTest>
+#include "../../src/core/translator.h"
+
+class TestTranslator : public QObject
+{
+    Q_OBJECT
+private slots:
+    void initTestCase();
+    void testLoadLanguage();
+    void testTranslation();
+    void testCleanup();
+};
+
+void TestTranslator::initTestCase()
+{
+    // Ensure we start with a clean state (singleton may persist)
+    // Since Translator is a singleton, we can reload language.
+    Translator& translator = Translator::instance();
+    translator.loadLanguage("en_US");
+}
+
+void TestTranslator::testLoadLanguage()
+{
+    Translator& translator = Translator::instance();
+    QVERIFY(translator.loadLanguage("en_US"));
+    QCOMPARE(translator.currentLanguage(), QString("en_US"));
+}
+
+void TestTranslator::testTranslation()
+{
+    Translator& translator = Translator::instance();
+    // Test known keys
+    QCOMPARE(translator.tr("appName"), QString("Wino Mail"));
+    QCOMPARE(translator.tr("welcomeMessage"), QString("Welcome to Wino Mail"));
+    QCOMPARE(translator.tr("inbox"), QString("Inbox"));
+    QCOMPARE(translator.tr("settings"), QString("Settings"));
+    // Test unknown key returns the key itself
+    QCOMPARE(translator.tr("unknown.key"), QString("unknown.key"));
+}
+
+void TestTranslator::testCleanup()
+{
+    // Nothing to clean up
+}
+
+QTEST_MAIN(TestTranslator)
+#include "test_translator.moc"