diff --git a/app/src/test/java/com/d4rk/androidtutorials/java/ui/screens/onboarding/OnboardingViewModelTest.java b/app/src/test/java/com/d4rk/androidtutorials/java/ui/screens/onboarding/OnboardingViewModelTest.java
new file mode 100644
index 00000000..b81c502c
--- /dev/null
+++ b/app/src/test/java/com/d4rk/androidtutorials/java/ui/screens/onboarding/OnboardingViewModelTest.java
@@ -0,0 +1,223 @@
+package com.d4rk.androidtutorials.java.ui.screens.onboarding;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.clearInvocations;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.res.Resources;
+
+import androidx.appcompat.app.AppCompatDelegate;
+import androidx.preference.PreferenceManager;
+
+import com.d4rk.androidtutorials.java.R;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockedStatic;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public class OnboardingViewModelTest {
+
+    private static final String THEME_KEY = "theme";
+    private static final String DEFAULT_TAB_KEY = "default_tab";
+    private static final String BOTTOM_NAV_LABELS_KEY = "labels";
+    private static final String MONOSPACE_FONT_KEY = "monospace_font";
+    private static final String CRASHLYTICS_KEY = "firebase_crashlytics";
+    private static final String CONSENT_ANALYTICS_KEY = "consent_analytics_storage";
+    private static final String CONSENT_AD_STORAGE_KEY = "consent_ad_storage";
+    private static final String CONSENT_AD_USER_DATA_KEY = "consent_ad_user_data";
+    private static final String CONSENT_AD_PERSONALIZATION_KEY = "consent_ad_personalization";
+    private static final String ONBOARDING_COMPLETE_KEY = "onboarding_complete";
+
+    private static final String[] THEME_VALUES = new String[]{"MODE_NIGHT_FOLLOW_SYSTEM", "MODE_NIGHT_NO"};
+    private static final String[] TAB_VALUES = new String[]{"home", "android_studio"};
+    private static final String[] BOTTOM_NAV_LABEL_VALUES = new String[]{"labeled", "selected"};
+    private static final String[] CODE_FONT_VALUES = new String[]{"0", "1"};
+
+    @Mock
+    private Context context;
+
+    @Mock
+    private Resources resources;
+
+    @Mock
+    private SharedPreferences sharedPreferences;
+
+    @Mock
+    private SharedPreferences.Editor editor;
+
+    private MockedStatic<PreferenceManager> preferenceManagerMock;
+    private MockedStatic<AppCompatDelegate> appCompatDelegateMock;
+
+    @Before
+    public void setUp() {
+        when(context.getResources()).thenReturn(resources);
+
+        when(sharedPreferences.edit()).thenReturn(editor);
+        when(editor.putString(anyString(), anyString())).thenReturn(editor);
+        when(editor.putBoolean(anyString(), anyBoolean())).thenReturn(editor);
+
+        when(context.getString(R.string.key_theme)).thenReturn(THEME_KEY);
+        when(context.getString(R.string.key_default_tab)).thenReturn(DEFAULT_TAB_KEY);
+        when(context.getString(R.string.key_bottom_navigation_bar_labels)).thenReturn(BOTTOM_NAV_LABELS_KEY);
+        when(context.getString(R.string.key_monospace_font)).thenReturn(MONOSPACE_FONT_KEY);
+        when(context.getString(R.string.key_firebase_crashlytics)).thenReturn(CRASHLYTICS_KEY);
+        when(context.getString(R.string.key_consent_analytics)).thenReturn(CONSENT_ANALYTICS_KEY);
+        when(context.getString(R.string.key_consent_ad_storage)).thenReturn(CONSENT_AD_STORAGE_KEY);
+        when(context.getString(R.string.key_consent_ad_user_data)).thenReturn(CONSENT_AD_USER_DATA_KEY);
+        when(context.getString(R.string.key_consent_ad_personalization)).thenReturn(CONSENT_AD_PERSONALIZATION_KEY);
+        when(context.getString(R.string.key_onboarding_complete)).thenReturn(ONBOARDING_COMPLETE_KEY);
+
+        when(resources.getStringArray(R.array.preference_theme_values)).thenReturn(THEME_VALUES);
+        when(resources.getStringArray(R.array.preference_default_tab_values)).thenReturn(TAB_VALUES);
+        when(resources.getStringArray(R.array.preference_bottom_navigation_bar_labels_values)).thenReturn(BOTTOM_NAV_LABEL_VALUES);
+        when(resources.getStringArray(R.array.code_font_values)).thenReturn(CODE_FONT_VALUES);
+
+        preferenceManagerMock = mockStatic(PreferenceManager.class);
+        preferenceManagerMock.when(() -> PreferenceManager.getDefaultSharedPreferences(context)).thenReturn(sharedPreferences);
+
+        appCompatDelegateMock = mockStatic(AppCompatDelegate.class);
+    }
+
+    @After
+    public void tearDown() {
+        preferenceManagerMock.close();
+        appCompatDelegateMock.close();
+    }
+
+    private OnboardingViewModel createViewModelWithExistingPrefs() {
+        when(sharedPreferences.contains(THEME_KEY)).thenReturn(true);
+        when(sharedPreferences.contains(DEFAULT_TAB_KEY)).thenReturn(true);
+        return new OnboardingViewModel(context);
+    }
+
+    @Test
+    public void constructor_initializesDefaults_whenPreferencesMissing() {
+        when(sharedPreferences.contains(THEME_KEY)).thenReturn(false);
+        when(sharedPreferences.contains(DEFAULT_TAB_KEY)).thenReturn(false);
+
+        new OnboardingViewModel(context);
+
+        appCompatDelegateMock.verify(() -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM));
+        verify(editor).putString(THEME_KEY, THEME_VALUES[0]);
+        verify(editor).putString(DEFAULT_TAB_KEY, TAB_VALUES[0]);
+        verify(editor, times(2)).apply();
+    }
+
+    @Test
+    public void setTheme_persistsValue_andGetThemeReturnsValue() {
+        OnboardingViewModel viewModel = createViewModelWithExistingPrefs();
+        clearInvocations(editor, sharedPreferences);
+
+        String newTheme = THEME_VALUES[1];
+        viewModel.setTheme(newTheme);
+
+        verify(editor).putString(THEME_KEY, newTheme);
+        verify(editor).apply();
+
+        when(sharedPreferences.getString(THEME_KEY, THEME_VALUES[0])).thenReturn(newTheme);
+
+        assertEquals(newTheme, viewModel.getTheme());
+        verify(sharedPreferences).getString(THEME_KEY, THEME_VALUES[0]);
+    }
+
+    @Test
+    public void setDefaultTab_persistsValue() {
+        OnboardingViewModel viewModel = createViewModelWithExistingPrefs();
+        clearInvocations(editor);
+
+        String newTab = TAB_VALUES[1];
+        viewModel.setDefaultTab(newTab);
+
+        verify(editor).putString(DEFAULT_TAB_KEY, newTab);
+        verify(editor).apply();
+    }
+
+    @Test
+    public void setBottomNavLabels_persistsValue_andGetBottomNavLabelsReturnsValue() {
+        OnboardingViewModel viewModel = createViewModelWithExistingPrefs();
+        clearInvocations(editor, sharedPreferences);
+
+        String newValue = BOTTOM_NAV_LABEL_VALUES[1];
+        viewModel.setBottomNavLabels(newValue);
+
+        verify(editor).putString(BOTTOM_NAV_LABELS_KEY, newValue);
+        verify(editor).apply();
+
+        when(sharedPreferences.getString(BOTTOM_NAV_LABELS_KEY, BOTTOM_NAV_LABEL_VALUES[0])).thenReturn(newValue);
+
+        assertEquals(newValue, viewModel.getBottomNavLabels());
+        verify(sharedPreferences).getString(BOTTOM_NAV_LABELS_KEY, BOTTOM_NAV_LABEL_VALUES[0]);
+    }
+
+    @Test
+    public void setMonospaceFont_persistsValue_andGetMonospaceFontReturnsValue() {
+        OnboardingViewModel viewModel = createViewModelWithExistingPrefs();
+        clearInvocations(editor, sharedPreferences);
+
+        String newFont = CODE_FONT_VALUES[1];
+        viewModel.setMonospaceFont(newFont);
+
+        verify(editor).putString(MONOSPACE_FONT_KEY, newFont);
+        verify(editor).apply();
+
+        when(sharedPreferences.getString(MONOSPACE_FONT_KEY, CODE_FONT_VALUES[0])).thenReturn(newFont);
+
+        assertEquals(newFont, viewModel.getMonospaceFont());
+        verify(sharedPreferences).getString(MONOSPACE_FONT_KEY, CODE_FONT_VALUES[0]);
+    }
+
+    @Test
+    public void booleanSetters_persistValues() {
+        OnboardingViewModel viewModel = createViewModelWithExistingPrefs();
+        clearInvocations(editor);
+
+        viewModel.setCrashlyticsEnabled(true);
+        verify(editor).putBoolean(CRASHLYTICS_KEY, true);
+
+        viewModel.setConsentAnalytics(false);
+        verify(editor).putBoolean(CONSENT_ANALYTICS_KEY, false);
+
+        viewModel.setConsentAdStorage(true);
+        verify(editor).putBoolean(CONSENT_AD_STORAGE_KEY, true);
+
+        viewModel.setConsentAdUserData(false);
+        verify(editor).putBoolean(CONSENT_AD_USER_DATA_KEY, false);
+
+        viewModel.setConsentAdPersonalization(true);
+        verify(editor).putBoolean(CONSENT_AD_PERSONALIZATION_KEY, true);
+
+        verify(editor, times(5)).apply();
+    }
+
+    @Test
+    public void markOnboardingComplete_persistsFlag() {
+        OnboardingViewModel viewModel = createViewModelWithExistingPrefs();
+        clearInvocations(editor);
+
+        viewModel.markOnboardingComplete();
+
+        verify(editor).putBoolean(ONBOARDING_COMPLETE_KEY, true);
+        verify(editor).apply();
+    }
+
+    @Test
+    public void setCurrentPage_updatesState() {
+        OnboardingViewModel viewModel = createViewModelWithExistingPrefs();
+
+        viewModel.setCurrentPage(2);
+
+        assertEquals(2, viewModel.getCurrentPage());
+    }
+}