diff --git a/walkguide-backend/demo/src/test/java/com/walkguide/service/MockDataServiceTest.java b/walkguide-backend/demo/src/test/java/com/walkguide/service/MockDataServiceTest.java
new file mode 100644
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--- /dev/null
+++ b/walkguide-backend/demo/src/test/java/com/walkguide/service/MockDataServiceTest.java
@@ -0,0 +1,270 @@
+package com.walkguide.service;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.*;
+
+@DisplayName("MockDataService Unit Tests")
+class MockDataServiceTest {
+
+    private MockDataService mockDataService;
+
+    @BeforeEach
+    void setUp() {
+        mockDataService = new MockDataService();
+    }
+
+    // ===== getUserStatus TESTS =====
+
+    @Test
+    @DisplayName("getUserStatus - harus return data status user yang sudah diinisialisasi")
+    void getUserStatus_shouldReturnInitializedUserStatus() {
+        Map<String, Object> status = mockDataService.getUserStatus();
+
+        assertThat(status).isNotNull();
+        assertThat(status).containsKey("status");
+        assertThat(status).containsKey("location");
+        assertThat(status).containsKey("batteryLevel");
+        assertThat(status).containsKey("lastSeen");
+    }
+
+    @Test
+    @DisplayName("getUserStatus - nilai default status harus 'Sedang Berjalan'")
+    void getUserStatus_defaultStatus_shouldBeSedangBerjalan() {
+        Map<String, Object> status = mockDataService.getUserStatus();
+
+        assertThat(status.get("status")).isEqualTo("Sedang Berjalan");
+    }
+
+    @Test
+    @DisplayName("getUserStatus - nilai default location harus 'Jl. Kenangan, SBY'")
+    void getUserStatus_defaultLocation_shouldBeJlKenangan() {
+        Map<String, Object> status = mockDataService.getUserStatus();
+
+        assertThat(status.get("location")).isEqualTo("Jl. Kenangan, SBY");
+    }
+
+    @Test
+    @DisplayName("getUserStatus - nilai default batteryLevel harus 85")
+    void getUserStatus_defaultBatteryLevel_shouldBe85() {
+        Map<String, Object> status = mockDataService.getUserStatus();
+
+        assertThat(status.get("batteryLevel")).isEqualTo(85);
+    }
+
+    @Test
+    @DisplayName("getUserStatus - nilai default lastSeen harus berupa timestamp ISO 8601")
+    void getUserStatus_defaultLastSeen_shouldBeIsoTimestamp() {
+        Map<String, Object> status = mockDataService.getUserStatus();
+
+        assertThat(status.get("lastSeen")).isEqualTo("2026-04-23T08:40:00Z");
+    }
+
+    @Test
+    @DisplayName("getUserStatus - harus return referensi map yang sama (stateful)")
+    void getUserStatus_shouldReturnSameMapReference() {
+        Map<String, Object> first = mockDataService.getUserStatus();
+        Map<String, Object> second = mockDataService.getUserStatus();
+
+        assertThat(first).isSameAs(second);
+    }
+
+    // ===== updateShortcuts TESTS =====
+
+    @Test
+    @DisplayName("updateShortcuts - harus menambahkan entry baru ke hardwareShortcuts")
+    void updateShortcuts_newEntry_shouldBeAdded() {
+        Map<String, Object> newShortcuts = new HashMap<>();
+        newShortcuts.put("volumeUpAction", "start_navigation");
+        newShortcuts.put("powerAction", "send_sos");
+
+        Map<String, Object> result = mockDataService.updateShortcuts(newShortcuts);
+
+        assertThat(result.get("volumeUpAction")).isEqualTo("start_navigation");
+        assertThat(result.get("powerAction")).isEqualTo("send_sos");
+    }
+
+    @Test
+    @DisplayName("updateShortcuts - nilai lama harus ter-override dengan nilai baru")
+    void updateShortcuts_existingKey_shouldBeOverridden() {
+        Map<String, Object> update = new HashMap<>();
+        update.put("volumeUpAction", "call_guardian"); // override dari "accept_call"
+
+        Map<String, Object> result = mockDataService.updateShortcuts(update);
+
+        assertThat(result.get("volumeUpAction")).isEqualTo("call_guardian");
+    }
+
+    @Test
+    @DisplayName("updateShortcuts - key yang tidak diupdate harus tetap ada")
+    void updateShortcuts_unrelatedKeys_shouldBePreserved() {
+        Map<String, Object> update = new HashMap<>();
+        update.put("volumeUpAction", "call_guardian");
+        // volumeDownAction tidak diubah
+
+        Map<String, Object> result = mockDataService.updateShortcuts(update);
+
+        assertThat(result.get("volumeDownAction")).isEqualTo("emergency_ping");
+    }
+
+    @Test
+    @DisplayName("updateShortcuts - harus return map yang sama (bukan salinan baru)")
+    void updateShortcuts_shouldReturnSameMapInstance() {
+        Map<String, Object> before = mockDataService.updateShortcuts(new HashMap<>());
+        Map<String, Object> after = mockDataService.updateShortcuts(new HashMap<>());
+
+        assertThat(before).isSameAs(after);
+    }
+
+    @Test
+    @DisplayName("updateShortcuts - default awal volumeUpAction harus 'accept_call'")
+    void updateShortcuts_defaultVolumeUpAction_shouldBeAcceptCall() {
+        Map<String, Object> result = mockDataService.updateShortcuts(new HashMap<>());
+
+        assertThat(result.get("volumeUpAction")).isEqualTo("accept_call");
+    }
+
+    @Test
+    @DisplayName("updateShortcuts - default awal volumeDownAction harus 'emergency_ping'")
+    void updateShortcuts_defaultVolumeDownAction_shouldBeEmergencyPing() {
+        Map<String, Object> result = mockDataService.updateShortcuts(new HashMap<>());
+
+        assertThat(result.get("volumeDownAction")).isEqualTo("emergency_ping");
+    }
+
+    @Test
+    @DisplayName("updateShortcuts - update dengan map kosong tidak boleh mengubah nilai yang ada")
+    void updateShortcuts_emptyMap_shouldNotModifyExistingValues() {
+        Map<String, Object> result = mockDataService.updateShortcuts(new HashMap<>());
+
+        assertThat(result.get("volumeUpAction")).isEqualTo("accept_call");
+        assertThat(result.get("volumeDownAction")).isEqualTo("emergency_ping");
+    }
+
+    @Test
+    @DisplayName("updateShortcuts - update berulang harus accumulate semua perubahan")
+    void updateShortcuts_multipleUpdates_shouldAccumulateChanges() {
+        mockDataService.updateShortcuts(Map.of("cameraAction", "take_photo"));
+        mockDataService.updateShortcuts(Map.of("homeAction", "open_walkguide"));
+
+        Map<String, Object> result = mockDataService.updateShortcuts(new HashMap<>());
+
+        assertThat(result.get("cameraAction")).isEqualTo("take_photo");
+        assertThat(result.get("homeAction")).isEqualTo("open_walkguide");
+    }
+
+    // ===== updateAiSettings TESTS =====
+
+    @Test
+    @DisplayName("updateAiSettings - harus menambahkan entry baru ke aiSettings")
+    void updateAiSettings_newEntry_shouldBeAdded() {
+        Map<String, Object> newSettings = new HashMap<>();
+        newSettings.put("speechRate", 1.5);
+        newSettings.put("language", "id-ID");
+
+        Map<String, Object> result = mockDataService.updateAiSettings(newSettings);
+
+        assertThat(result.get("speechRate")).isEqualTo(1.5);
+        assertThat(result.get("language")).isEqualTo("id-ID");
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - nilai lama harus ter-override dengan nilai baru")
+    void updateAiSettings_existingKey_shouldBeOverridden() {
+        Map<String, Object> update = new HashMap<>();
+        update.put("alertDistanceMeters", 5.0); // override dari 2.5
+
+        Map<String, Object> result = mockDataService.updateAiSettings(update);
+
+        assertThat(result.get("alertDistanceMeters")).isEqualTo(5.0);
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - key yang tidak diupdate harus tetap ada")
+    void updateAiSettings_unrelatedKeys_shouldBePreserved() {
+        Map<String, Object> update = new HashMap<>();
+        update.put("alertDistanceMeters", 3.0);
+        // hapticFeedback tidak diubah
+
+        Map<String, Object> result = mockDataService.updateAiSettings(update);
+
+        assertThat(result.get("hapticFeedback")).isEqualTo(true);
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - default alertDistanceMeters harus 2.5")
+    void updateAiSettings_defaultAlertDistance_shouldBe2point5() {
+        Map<String, Object> result = mockDataService.updateAiSettings(new HashMap<>());
+
+        assertThat(result.get("alertDistanceMeters")).isEqualTo(2.5);
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - default hapticFeedback harus true")
+    void updateAiSettings_defaultHapticFeedback_shouldBeTrue() {
+        Map<String, Object> result = mockDataService.updateAiSettings(new HashMap<>());
+
+        assertThat(result.get("hapticFeedback")).isEqualTo(true);
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - harus return map yang sama (bukan salinan baru)")
+    void updateAiSettings_shouldReturnSameMapInstance() {
+        Map<String, Object> before = mockDataService.updateAiSettings(new HashMap<>());
+        Map<String, Object> after = mockDataService.updateAiSettings(new HashMap<>());
+
+        assertThat(before).isSameAs(after);
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - update dengan map kosong tidak boleh mengubah nilai yang ada")
+    void updateAiSettings_emptyMap_shouldNotModifyExistingValues() {
+        Map<String, Object> result = mockDataService.updateAiSettings(new HashMap<>());
+
+        assertThat(result.get("alertDistanceMeters")).isEqualTo(2.5);
+        assertThat(result.get("hapticFeedback")).isEqualTo(true);
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - update boolean ke false harus tersimpan dengan benar")
+    void updateAiSettings_disableHapticFeedback_shouldBeFalse() {
+        Map<String, Object> update = new HashMap<>();
+        update.put("hapticFeedback", false);
+
+        Map<String, Object> result = mockDataService.updateAiSettings(update);
+
+        assertThat(result.get("hapticFeedback")).isEqualTo(false);
+    }
+
+    @Test
+    @DisplayName("updateAiSettings - update berulang harus accumulate semua perubahan")
+    void updateAiSettings_multipleUpdates_shouldAccumulateChanges() {
+        mockDataService.updateAiSettings(Map.of("confidenceThreshold", 0.85));
+        mockDataService.updateAiSettings(Map.of("maxObstacleRange", 10));
+
+        Map<String, Object> result = mockDataService.updateAiSettings(new HashMap<>());
+
+        assertThat(result.get("confidenceThreshold")).isEqualTo(0.85);
+        assertThat(result.get("maxObstacleRange")).isEqualTo(10);
+    }
+
+    // ===== Isolation Tests =====
+
+    @Test
+    @DisplayName("instance baru harus selalu punya data default yang segar")
+    void newInstance_shouldAlwaysHaveFreshDefaultData() {
+        MockDataService instance1 = new MockDataService();
+        MockDataService instance2 = new MockDataService();
+
+        instance1.updateShortcuts(Map.of("volumeUpAction", "changed_action"));
+
+        // instance2 tidak terpengaruh perubahan instance1
+        assertThat(instance2.updateShortcuts(new HashMap<>()).get("volumeUpAction"))
+                .isEqualTo("accept_call");
+    }
+}