RUBY-403 added test and fix for refresh health check attempting to close socket that may be nil

lib/mongo/util/node.rb

@@ -101,7 +101,12 @@ module Mongo
       rescue ConnectionFailure, OperationFailure, OperationTimeout, SocketError, SystemCallError, IOError => ex
         @connection.log(:warn, "Attempted connection to node #{host_string} raised " +
                             "#{ex.class}: #{ex.message}")
-        @socket.close unless @socket.closed?
+        
+        # Socket may already be nil from issuing command
+        if @socket && !@socket.closed?
+          @socket.close
+        end
+        
         return nil
       end
 

test/replica_sets/refresh_test.rb

@@ -99,6 +99,28 @@ class ReplicaSetRefreshTest < Test::Unit::TestCase
       "Read pool and primary pool are identical."
   end
   
+  def test_automated_refresh_when_secondary_goes_down
+    @conn = ReplSetConnection.new([self.rs.host, self.rs.ports[0]],
+                                  [self.rs.host, self.rs.ports[1]],
+                                  [self.rs.host, self.rs.ports[2]],
+                                  :refresh_interval => 2,
+                                  :refresh_mode => :sync)
+
+    num_secondaries = @conn.secondary_pools.length
+    old_refresh_version = @conn.refresh_version
+
+    n = self.rs.kill_secondary
+    sleep(4)
+    @conn['foo']['bar'].find_one
+
+    assert @conn.refresh_version > old_refresh_version,
+      "Refresh version hasn't changed."
+    assert_equal num_secondaries - 1, @conn.secondaries.length
+    assert_equal num_secondaries - 1, @conn.secondary_pools.length
+
+    self.rs.restart_killed_nodes
+  end
+
   def test_automated_refresh_with_removed_node
     @conn = ReplSetConnection.new([self.rs.host, self.rs.ports[0]],
                                   [self.rs.host, self.rs.ports[1]],