RUBY-900 Don't add discovered servers to the cluster with Single topology

Author: estolfo

lib/mongo/address.rb

@@ -33,7 +33,7 @@ class Address
                    ::Socket::AF_INET => IPv4
                  }
 
-    # @return [ String ] address The seed address.
+    # @return [ String ] seed The seed address.
     attr_reader :seed
 
     # @return [ String ] host The original host name.

lib/mongo/cluster.rb

@@ -66,7 +66,7 @@ def ==(other)
     # @since 2.0.0
     def add(host)
       address = Address.new(host)
-      unless addresses.include?(address)
+      unless addresses.include?(address) || (@topology.single? && address.seed != @topology.seed)
         log_debug([ "Adding #{address.to_s} to the cluster." ])
         addresses.push(address)
         server = Server.new(address, event_listeners,

lib/mongo/cluster/topology.rb

@@ -48,12 +48,12 @@ module Topology
       # @since 2.0.0
       def initial(seeds, options)
         if options.has_key?(:connect)
-          return OPTIONS.fetch(options[:connect]).new(options)
+          return OPTIONS.fetch(options[:connect]).new(options, seeds)
         end
         if options.has_key?(:replica_set)
-          ReplicaSet.new(options)
+          ReplicaSet.new(options, seeds)
         else
-          seeds.size > 1 ? Unknown.new(options) : Single.new(options)
+          seeds.size > 1 ? Unknown.new(options, seeds) : Single.new(options, seeds)
         end
       end
     end

lib/mongo/cluster/topology/replica_set.rb

@@ -82,7 +82,7 @@ def elect_primary(description, servers)
         # @param [ Hash ] options The options.
         #
         # @since 2.0.0
-        def initialize(options)
+        def initialize(options, seeds = [])
           @options = options
         end
 

lib/mongo/cluster/topology/sharded.rb

@@ -59,7 +59,7 @@ def elect_primary(description, servers); self; end
         # @param [ Hash ] options The options.
         #
         # @since 2.0.0
-        def initialize(options)
+        def initialize(options, seeds = [])
           @options = options
         end
 

lib/mongo/cluster/topology/single.rb

@@ -21,6 +21,9 @@ module Topology
       # @since 2.0.0
       class Single
 
+        # @return [ String ] seed The seed address.
+        attr_reader :seed
+
         # The display name for the topology.
         #
         # @since 2.0.0
@@ -59,8 +62,9 @@ def elect_primary(description, servers); self; end
         # @param [ Hash ] options The options.
         #
         # @since 2.0.0
-        def initialize(options)
+        def initialize(options, seeds = [])
           @options = options
+          @seed = seeds.first
         end
 
         # A single topology is not a replica set.

lib/mongo/cluster/topology/unknown.rb

@@ -70,7 +70,7 @@ def elect_primary(description, servers)
         # @param [ Hash ] options The options.
         #
         # @since 2.0.0
-        def initialize(options)
+        def initialize(options, seeds = [])
           @options = options
         end