throw exception if JedisCluster cannot connect to any host-port (#2721)

Original PR: #2275 
Original author: @chinafzy 

If none of the `startNodes`, given in JedisCluster constructor, works:
- JedisCluster does not work.
- No message/exception comes up.
- JedisCluster cannot not retry later.

User would be instantly aware if an exception is thrown.

Co-authored-by: fangzeyu <zeyu.fang@chelaile.net.cn>

src/main/java/redis/clients/jedis/providers/ClusterConnectionProvider.java

@@ -45,6 +45,8 @@ private void initializeSlotsCache(Set<HostAndPort> startNodes, JedisClientConfig
         // try next nodes
       }
     }
+
+    throw new JedisClusterOperationException("Could not initialize cluster slots cache.");
   }
 
   @Override

src/test/java/redis/clients/jedis/JedisClusterWithoutSetupTest.java

@@ -0,0 +1,13 @@
+package redis.clients.jedis;
+
+import org.junit.Test;
+
+import redis.clients.jedis.exceptions.JedisClusterOperationException;
+
+public class JedisClusterWithoutSetupTest {
+
+  @Test(expected = JedisClusterOperationException.class)
+  public void uselessStartNodes() {
+    new JedisCluster(new HostAndPort("localhost", 7378));
+  }
+}

src/test/java/redis/clients/jedis/SSLACLJedisClusterTest.java

@@ -139,11 +139,12 @@ public void connectByIpAddressFailsWithSSLParameters() {
         DefaultJedisClientConfig.builder().user("default").password("cluster").ssl(true)
             .sslParameters(sslParameters).hostAndPortMapper(hostAndPortMap).build(),
         DEFAULT_REDIRECTIONS, DEFAULT_POOL_CONFIG)) {
-      jc.get("key");
-      Assert.fail("There should be no reachable node in cluster.");
-//    } catch (JedisNoReachableClusterNodeException e) {
+//      jc.get("key");
+//      Assert.fail("There should be no reachable node in cluster.");
+////    } catch (JedisNoReachableClusterNodeException e) {
     } catch (JedisClusterOperationException e) {
-      assertEquals("No reachable node in cluster.", e.getMessage());
+//      assertEquals("No reachable node in cluster.", e.getMessage());
+      assertEquals("Could not initialize cluster slots cache.", e.getMessage());
     }
   }
 
@@ -169,13 +170,14 @@ public void connectWithCustomHostNameVerifier() {
         DefaultJedisClientConfig.builder().user("default").password("cluster").ssl(true)
             .hostnameVerifier(hostnameVerifier).hostAndPortMapper(portMap).build(),
         DEFAULT_REDIRECTIONS, DEFAULT_POOL_CONFIG)) {
-      jc2.get("key");
-      Assert.fail("There should be no reachable node in cluster.");
-//    } catch (JedisNoReachableClusterNodeException e) {
+//      jc2.get("key");
+//      Assert.fail("There should be no reachable node in cluster.");
+////    } catch (JedisNoReachableClusterNodeException e) {
     } catch (JedisClusterOperationException e) {
       // JedisNoReachableClusterNodeException exception occurs from not being able to connect since
       // the socket factory fails the hostname verification
-      assertEquals("No reachable node in cluster.", e.getMessage());
+//      assertEquals("No reachable node in cluster.", e.getMessage());
+      assertEquals("Could not initialize cluster slots cache.", e.getMessage());
     }
 
     try (JedisCluster jc3 = new JedisCluster(new HostAndPort("localhost", 8379),
@@ -205,11 +207,12 @@ public void connectWithEmptyTrustStore() throws Exception {
     try (JedisCluster jc = new JedisCluster(new HostAndPort("localhost", 8379),
         DefaultJedisClientConfig.builder().user("default").password("cluster").ssl(true)
             .sslSocketFactory(sslSocketFactory).build(), DEFAULT_REDIRECTIONS, DEFAULT_POOL_CONFIG)) {
-      jc.get("key");
-      Assert.fail("There should be no reachable node in cluster.");
-//    } catch (JedisNoReachableClusterNodeException e) {
+//      jc.get("key");
+//      Assert.fail("There should be no reachable node in cluster.");
+////    } catch (JedisNoReachableClusterNodeException e) {
     } catch (JedisClusterOperationException e) {
-      assertEquals("No reachable node in cluster.", e.getMessage());
+//      assertEquals("No reachable node in cluster.", e.getMessage());
+      assertEquals("Could not initialize cluster slots cache.", e.getMessage());
     }
   }
 

src/test/java/redis/clients/jedis/SSLJedisClusterTest.java

@@ -138,11 +138,12 @@ public void connectByIpAddressFailsWithSSLParameters() {
         DefaultJedisClientConfig.builder().password("cluster").ssl(true)
             .sslParameters(sslParameters).hostAndPortMapper(hostAndPortMap).build(),
         DEFAULT_REDIRECTIONS, DEFAULT_POOL_CONFIG)) {
-      jc.get("key");
-      Assert.fail("There should be no reachable node in cluster.");
-//    } catch (JedisNoReachableClusterNodeException e) {
+//      jc.get("key");
+//      Assert.fail("There should be no reachable node in cluster.");
+////    } catch (JedisNoReachableClusterNodeException e) {
     } catch (JedisClusterOperationException e) {
-      assertEquals("No reachable node in cluster.", e.getMessage());
+//      assertEquals("No reachable node in cluster.", e.getMessage());
+      assertEquals("Could not initialize cluster slots cache.", e.getMessage());
     }
   }
 
@@ -168,13 +169,14 @@ public void connectWithCustomHostNameVerifier() {
         DefaultJedisClientConfig.builder().password("cluster").ssl(true)
             .hostnameVerifier(hostnameVerifier).hostAndPortMapper(portMap).build(),
         DEFAULT_REDIRECTIONS, DEFAULT_POOL_CONFIG)) {
-      jc2.get("foo");
-      Assert.fail("There should be no reachable node in cluster.");
-//    } catch (JedisNoReachableClusterNodeException e) {
+//      jc2.get("foo");
+//      Assert.fail("There should be no reachable node in cluster.");
+////    } catch (JedisNoReachableClusterNodeException e) {
     } catch (JedisClusterOperationException e) {
       // JedisNoReachableClusterNodeException exception occurs from not being able to connect
       // since the socket factory fails the hostname verification
-      assertEquals("No reachable node in cluster.", e.getMessage());
+//      assertEquals("No reachable node in cluster.", e.getMessage());
+      assertEquals("Could not initialize cluster slots cache.", e.getMessage());
     }
 
     try (JedisCluster jc3 = new JedisCluster(new HostAndPort("localhost", 8379),
@@ -204,11 +206,12 @@ public void connectWithEmptyTrustStore() throws Exception {
     try (JedisCluster jc = new JedisCluster(new HostAndPort("localhost", 8379),
         DefaultJedisClientConfig.builder().password("cluster").ssl(true)
             .sslSocketFactory(sslSocketFactory).build(), DEFAULT_REDIRECTIONS, DEFAULT_POOL_CONFIG)) {
-      jc.get("key");
-      Assert.fail("There should be no reachable node in cluster.");
-//    } catch (JedisNoReachableClusterNodeException e) {
+//      jc.get("key");
+//      Assert.fail("There should be no reachable node in cluster.");
+////    } catch (JedisNoReachableClusterNodeException e) {
     } catch (JedisClusterOperationException e) {
-      assertEquals("No reachable node in cluster.", e.getMessage());
+//      assertEquals("No reachable node in cluster.", e.getMessage());
+      assertEquals("Could not initialize cluster slots cache.", e.getMessage());
     }
   }