test: add unit tests for HomeboxSearchProvider and SearchResponse

HomeboxSearchProviderTest verifies that ConnectionNotFoundException is
thrown when no matching connection exists in the repository.
SearchResponseTest covers the getExtra helper — null extra map, missing
key, and a present key.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/test/java/com/vaessl/app/search/HomeboxSearchProviderTest.java

@@ -0,0 +1,35 @@
+package com.vaessl.app.search;
+
+import static com.vaessl.app.Mockdata.*;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.when;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import com.vaessl.app.connection.ConnectionRepository;
+import com.vaessl.app.exception.ConnectionNotFoundException;
+
+@ExtendWith(MockitoExtension.class)
+class HomeboxSearchProviderTest {
+
+    @Mock
+    private ConnectionRepository mockRepo;
+
+    @InjectMocks
+    private HomeboxSearchProvider provider;
+
+    @Test
+    void shouldReturnConnectionNotFoundException() {
+
+        when(mockRepo.findByAppUrlAndUsername(MOCK_URL, MOCK_USER)).thenReturn(null);
+
+        SearchRequest request = new SearchRequest(MOCK_URL, MOCK_USER, "test query", "HOMEBOX");
+        Pageable pageable = PageRequest.of(0, 10);
+        assertThrows(ConnectionNotFoundException.class,
+                () -> provider.getSearchResults(request, pageable));
+    }
+}