test: enhance assertions in EtcdClientTest for better clarity and reliability

Author: Aias00

shenyu-registry/shenyu-registry-etcd/src/test/java/org/apache/shenyu/registry/etcd/EtcdClientTest.java

@@ -67,23 +67,33 @@ public void etcdClientTest() {
 
             when(client.getLeaseClient().grant(anyLong())).thenReturn(completableFuture);
             when(completableFuture.get()).thenReturn(leaseGrantResponse);
-            Assertions.assertDoesNotThrow(() -> EtcdClient.builder().client(Client.builder().endpoints("url").build()).ttl(60L).timeout(3000L).build());
-
             List<StreamObserver<LeaseKeepAliveResponse>> observerList = new ArrayList<>();
             doAnswer(invocation -> {
                 observerList.add(invocation.getArgument(1));
                 return lease;
             }).when(lease).keepAlive(anyLong(), any());
-            Assertions.assertDoesNotThrow(() -> EtcdClient.builder().client(Client.builder().endpoints("url").build()).ttl(60L).timeout(3000L).build());
+
+            final EtcdClient etcdClient = Assertions.assertDoesNotThrow(() -> EtcdClient.builder()
+                    .client(Client.builder().endpoints("url").build())
+                    .ttl(60L)
+                    .timeout(3000L)
+                    .build());
+            Assertions.assertNotNull(etcdClient);
+
             final LeaseKeepAliveResponse leaseKeepAliveResponse = mock(LeaseKeepAliveResponse.class);
             observerList.forEach(streamObserver -> {
                 streamObserver.onCompleted();
                 streamObserver.onError(new ShenyuException("test"));
                 streamObserver.onNext(leaseKeepAliveResponse);
             });
+            etcdClient.close();
 
             doThrow(new InterruptedException("error")).when(completableFuture).get();
-            Assertions.assertThrows(ShenyuException.class, () -> EtcdClient.builder().client(Client.builder().endpoints("url").build()).ttl(60L).timeout(3000L).build());
+            Assertions.assertThrows(ShenyuException.class, () -> EtcdClient.builder()
+                    .client(Client.builder().endpoints("url").build())
+                    .ttl(60L)
+                    .timeout(3000L)
+                    .build());
         } catch (Exception e) {
             throw new ShenyuException(e.getCause());
         }