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

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)
+      if !addresses.include?(address) || direct_connection?(address)
         log_debug([ "Adding #{address.to_s} to the cluster." ])
         addresses.push(address)
         server = Server.new(address, event_listeners,
@@ -201,5 +201,11 @@ def self.create(client)
       cluster = Cluster.new(client.cluster.addresses.map(&:to_s), client.options)
       client.instance_variable_set(:@cluster, cluster)
     end
+
+    private
+
+    def direct_connection?(address)
+      @topology.single? && address.seed == @topology.seed
+    end
   end
 end

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
 

spec/mongo/cluster/topology_spec.rb

@@ -24,6 +24,10 @@
       it 'returns a single topology' do
         expect(topology).to be_a(Mongo::Cluster::Topology::Single)
       end
+
+      it 'sets the seed on the topology' do
+        expect(topology.seed).to eq('a')
+      end
     end
 
     context 'when provided a sharded option' do

spec/mongo/cluster_spec.rb

@@ -2,11 +2,11 @@
 
 describe Mongo::Cluster do
 
-  describe '#==' do
+  let(:cluster) do
+    described_class.new(ADDRESSES)
+  end
 
-    let(:cluster) do
-      described_class.new([ '127.0.0.1:27017' ])
-    end
+  describe '#==' do
 
     context 'when the other is a cluster' do
 
@@ -61,10 +61,6 @@
       Mongo::ServerSelector.get
     end
 
-    let(:cluster) do
-      described_class.new([ '127.0.0.1:27017' ])
-    end
-
     it 'displays the cluster seeds and topology' do
       expect(cluster.inspect).to include('topology')
       expect(cluster.inspect).to include('servers')
@@ -78,13 +74,13 @@
     end
 
     let(:cluster) do
-      described_class.new([ '127.0.0.1:27017' ], :replica_set => 'testing')
+      described_class.new(ADDRESSES, :replica_set => 'testing')
     end
 
     context 'when the option is provided' do
 
       let(:cluster) do
-        described_class.new([ '127.0.0.1:27017' ], :replica_set => 'testing')
+        described_class.new(ADDRESSES, :replica_set => 'testing')
       end
 
       it 'returns the name' do
@@ -95,7 +91,7 @@
     context 'when the option is not provided' do
 
       let(:cluster) do
-        described_class.new([ '127.0.0.1:27017' ])
+        described_class.new(ADDRESSES)
       end
 
       it 'returns nil' do
@@ -110,10 +106,6 @@
       Mongo::ServerSelector.get
     end
 
-    let(:cluster) do
-      described_class.new([ '127.0.0.1:27017' ])
-    end
-
     let(:known_servers) do
       cluster.instance_variable_get(:@servers)
     end
@@ -131,10 +123,6 @@
 
     context 'when topology is single', if: single_seed? do
 
-      let(:cluster) do
-        described_class.new(ADDRESSES)
-      end
-
       context 'when the server is a mongos', if: single_mongos?  do
 
         it 'returns the mongos' do
@@ -152,10 +140,6 @@
 
     context 'when the cluster has no servers' do
 
-      let(:cluster) do
-        described_class.new(ADDRESSES)
-      end
-
       let(:servers) do
         [nil]
       end
@@ -210,4 +194,22 @@
       end
     end
   end
+
+  describe '#add' do
+
+    context 'when topology is Single' do
+
+      let(:topology) do
+        Mongo::Cluster::Topology::Single.new({})
+      end
+
+      before do
+        cluster.add('a')
+      end
+
+      it 'does not add discovered servers to the cluster' do
+        expect(cluster.servers[0].address.seed).to_not eq('a')
+      end
+    end
+  end
 end