Check decorated connection responds to open_transactions before invoking

lib/makara/connection_wrapper.rb

@@ -44,7 +44,7 @@ def _makara_blacklisted?
     end
 
     def _makara_in_transaction?
-      @connection && @connection.open_transactions > 0
+      @connection && @connection.respond_to?(:open_transactions) && @connection.open_transactions > 0
     end
 
     # blacklist this node for @config[:blacklist_duration] seconds

spec/connection_wrapper_spec.rb

@@ -1,7 +1,8 @@
 require 'spec_helper'
 
 describe Makara::ConnectionWrapper do
-  let(:proxy){ FakeProxy.new({makara: {blacklist_duration: 5, connections: [{role: 'primary'}, {role: 'replica'}, {role: 'replica'}]}}) }
+  let(:proxy_config){ {makara: {blacklist_duration: 5, connections: [{role: 'primary'}, {role: 'replica'}, {role: 'replica'}]}} }
+  let(:proxy){ FakeProxy.new(proxy_config) }
   let(:connection){ subject._makara_connection }
 
   subject{ proxy.primary_pool.connections.first }
@@ -39,4 +40,27 @@
       end
     end
   end
+
+  context '#_makara_in_transaction?' do
+    context 'open_transactions is 0' do
+      it 'should return false' do
+        expect(subject._makara_in_transaction?).to eq(false)
+      end
+    end
+
+    context 'connection does not respond to open_transactions' do
+      let(:non_ar_proxy) do
+        Class.new(FakeProxy) do
+          def connection_for(config)
+            FakeConnectionBase.new(config)
+          end
+        end
+      end
+      let(:proxy){ non_ar_proxy.new(proxy_config) }
+
+      it 'should return false' do
+        expect(subject._makara_in_transaction?).to eq(false)
+      end
+    end
+  end
 end

spec/support/mock_objects.rb

@@ -1,6 +1,6 @@
 require 'active_record/connection_adapters/makara_abstract_adapter'
 
-class FakeConnection < Struct.new(:config)
+class FakeConnectionBase < Struct.new(:config)
   def ping
     'ping!'
   end
@@ -17,10 +17,6 @@ def active?
     true
   end
 
-  def open_transactions
-    (config || {}).fetch(:open_transactions, 0)
-  end
-
   def disconnect!
     true
   end
@@ -30,6 +26,12 @@ def something
   end
 end
 
+class FakeConnection < FakeConnectionBase
+  def open_transactions
+    (config || {}).fetch(:open_transactions, 0)
+  end
+end
+
 class FakeDatabaseAdapter < Struct.new(:config)
   def execute(sql, name = nil)
     []