RUBY-891 Tests for Single topology with RS member and mongos

Author: estolfo

lib/mongo/cluster/topology.rb

@@ -40,6 +40,7 @@ module Topology
       # @example Get the initial cluster topology.
       #   Topology.initial(topology: :replica_set)
       #
+      # @param [ Array<String> ] seeds The addresses of the configured servers.
       # @param [ Hash ] options The cluster options.
       #
       # @return [ ReplicaSet, Sharded, Single ] The topology.

spec/mongo/cluster/topology_spec.rb

@@ -60,6 +60,28 @@
           expect(topology).to be_a(Mongo::Cluster::Topology::Single)
         end
       end
+
+      context 'when provided a single mongos', if: single_mongos? do
+
+        let(:topology) do
+          described_class.initial(ADDRESSES, {})
+        end
+
+        it 'returns a single topology' do
+          expect(topology).to be_a(Mongo::Cluster::Topology::Single)
+        end
+      end
+
+      context 'when provided a single replica set member', if: single_rs_member? do
+
+        let(:topology) do
+          described_class.initial(ADDRESSES, {})
+        end
+
+        it 'returns a single topology' do
+          expect(topology).to be_a(Mongo::Cluster::Topology::Single)
+        end
+      end
     end
   end
 end

spec/mongo/cluster_spec.rb

@@ -126,4 +126,28 @@
       expect(cluster.scan!).to be true
     end
   end
+
+  describe '#servers' do
+
+    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
+          expect(cluster.servers.size).to eq(1)
+        end
+      end
+
+      context 'when the server is a replica set member', if: single_rs_member? do
+
+        it 'returns the replica set member' do
+          expect(cluster.servers.size).to eq(1)
+        end
+      end
+    end
+  end
 end

spec/spec_helper.rb

@@ -99,6 +99,29 @@ def sharded?
   $sharded ||= $mongo_client.cluster.sharded?
 end
 
+# Determine whether the single address provided is a replica set member.
+#
+# @since 2.0.0
+def single_rs_member?
+  $mongo_client ||= initialize_scanned_client!
+  single_seed? && $mongo_client.cluster.servers.first.replica_set_name
+end
+
+# Determine whether the single address provided is a mongos.
+#
+# @since 2.0.0
+def single_mongos?
+  $mongo_client ||= initialize_scanned_client!
+  single_seed? && $mongo_client.cluster.servers.first.mongos?
+end
+
+# Determine whether a single address was provided.
+#
+# @since 2.0.0
+def single_seed?
+  ADDRESSES.size == 1
+end
+
 # For instances where behaviour is different on different versions, we need to
 # determine in the specs if we are 2.6 or higher.
 #