Please provide the specific file changes or a description of the modifications you have made so I can generate the commit message for you.

backend/src/test/java/com/sshmanager/service/ConnectionStatusServiceTest.java

@@ -0,0 +1,72 @@
+package com.sshmanager.service;
+
+import com.sshmanager.dto.ConnectionStatusCheckRequest;
+import com.sshmanager.dto.ConnectionStatusResponseDto;
+import com.sshmanager.entity.Connection;
+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 java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class ConnectionStatusServiceTest {
+
+    @Mock
+    private ConnectionService connectionService;
+
+    @InjectMocks
+    private ConnectionStatusService connectionStatusService;
+
+    @Test
+    void checkStatusesAggregatesOnlineAndOfflineResults() {
+        Connection onlineConnection = new Connection();
+        onlineConnection.setId(1L);
+        onlineConnection.setUserId(99L);
+        onlineConnection.setName("prod");
+
+        Connection offlineConnection = new Connection();
+        offlineConnection.setId(2L);
+        offlineConnection.setUserId(99L);
+        offlineConnection.setName("test");
+
+        ConnectionStatusCheckRequest request = new ConnectionStatusCheckRequest();
+        request.setConnectionIds(Arrays.asList(1L, 2L));
+
+        when(connectionService.getConnectionForSsh(1L, 99L)).thenReturn(onlineConnection);
+        when(connectionService.getConnectionForSsh(2L, 99L)).thenReturn(offlineConnection);
+        doReturn(onlineConnection).when(connectionService).testConnection(eq(onlineConnection), eq(null), eq(null), eq(null));
+        doThrow(new RuntimeException("Connection refused")).when(connectionService).testConnection(eq(offlineConnection), eq(null), eq(null), eq(null));
+
+        ConnectionStatusResponseDto response = connectionStatusService.checkStatuses(99L, request);
+
+        assertEquals(2, response.getTotal());
+        assertEquals(1, response.getOnlineCount());
+        assertEquals(1, response.getOfflineCount());
+        assertEquals("online", response.getResults().get(0).getStatus());
+        assertEquals("offline", response.getResults().get(1).getStatus());
+        assertEquals("prod", response.getResults().get(0).getConnectionName());
+        assertEquals("Connection refused", response.getResults().get(1).getMessage());
+    }
+
+    @Test
+    void checkStatusesRejectsEmptyConnectionIds() {
+        ConnectionStatusCheckRequest request = new ConnectionStatusCheckRequest();
+
+        IllegalArgumentException error = assertThrows(
+            IllegalArgumentException.class,
+            () -> connectionStatusService.checkStatuses(1L, request)
+        );
+
+        assertEquals("At least one connection is required", error.getMessage());
+    }
+}