增强 SSH/SFTP 稳定性并完善安全校验与前端交互

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

@@ -0,0 +1,51 @@
+package com.sshmanager.service;
+
+import com.sshmanager.entity.Connection;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class SftpServiceTest {
+
+    private SftpService sftpService;
+    private ExecutorService executorService;
+
+    @BeforeEach
+    void setUp() {
+        executorService = Executors.newFixedThreadPool(2);
+        sftpService = new SftpService();
+        sftpService.setExecutorService(executorService);
+    }
+
+    @Test
+    void testPasswordAuthenticationRequiredWithValidConnection() {
+        Exception exception = assertThrows(Exception.class, () -> {
+            Connection conn = new Connection();
+            conn.setHost("127.0.0.1");
+            conn.setPort(22);
+            conn.setUsername("test");
+            conn.setAuthType(Connection.AuthType.PASSWORD);
+            sftpService.connect(conn, "", null, null);
+        });
+        assertTrue(exception.getMessage().contains("Password is required") || 
+                   exception instanceof IllegalArgumentException);
+    }
+
+    @Test
+    void testPasswordAuthenticationRequiredWithNullConn() {
+        Exception exception = assertThrows(Exception.class, () -> {
+            sftpService.connect(null, "", null, null);
+        });
+        assertTrue(exception instanceof NullPointerException || exception instanceof IllegalArgumentException);
+    }
+
+    @Test
+    void testExecutorServiceShutdown() throws Exception {
+        executorService.shutdown();
+        assertTrue(executorService.isTerminated() || executorService.isShutdown());
+    }
+}