Move into MiniSQLMultisiteConnection, and add test for rollback

spec/lib/mini_sql_multisite_connection_spec.rb

@@ -0,0 +1,52 @@
+require 'rails_helper'
+
+describe MiniSqlMultisiteConnection do
+
+  describe "after_commit" do
+    it "runs callbacks after outermost transaction is committed" do
+      outputString = "1"
+
+      # Main transaction
+      ActiveRecord::Base.transaction do  
+        outputString += "2"
+
+          # Nested transaction
+          ActiveRecord::Base.transaction do
+            outputString += "3"
+
+              DB.after_commit do
+                outputString += "6"
+              end
+              outputString += "4"
+          end
+
+          DB.after_commit do
+            outputString += "7"
+          end
+
+          outputString += "5"
+      end
+
+      expect(outputString).to eq("1234567")
+    end
+
+    it "does not run if the transaction is rolled back" do
+      outputString = "1"
+
+      ActiveRecord::Base.transaction do
+        outputString += "2"
+
+        DB.after_commit do
+          outputString += "4"
+        end
+
+        outputString += "3"
+
+        raise ActiveRecord::Rollback
+      end
+
+      expect(outputString).to eq("123")
+    end
+  end
+
+end