HDFS-17830. Fix failing TestZKDelegationTokenSecretManagerImpl due to static Curator reuse. (#7960) Contributed by Hualong Zhang.

* HDFS-17830. Fix failing TestZKDelegationTokenSecretManagerImpl due to static Curator reuse. 

Signed-off-by: Shilun Fan <slfan1989@apache.org>

Author: zhtttylz

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/security/token/TestZKDelegationTokenSecretManagerImpl.java

@@ -32,9 +32,11 @@
 import org.apache.hadoop.security.token.SecretManager;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.delegation.TestZKDelegationTokenSecretManager;
+import org.apache.hadoop.security.token.delegation.ZKDelegationTokenSecretManager;
 import org.apache.hadoop.security.token.delegation.web.DelegationTokenIdentifier;
 import org.apache.hadoop.security.token.delegation.web.DelegationTokenManager;
 import org.apache.hadoop.util.Time;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -44,6 +46,14 @@ public class TestZKDelegationTokenSecretManagerImpl
   private static final Logger LOG =
       LoggerFactory.getLogger(TestZKDelegationTokenSecretManagerImpl.class);
 
+  @Override
+  @AfterEach
+  public void tearDown() throws Exception {
+    super.tearDown();
+    // Prevent a STOPPED Curator from leaking into the next test.
+    ZKDelegationTokenSecretManager.setCurator(null);
+  }
+
   @SuppressWarnings("unchecked")
   @Test
   public void testMultiNodeOperationWithoutWatch() throws Exception {