Add task to simulate data migration

This way we can check everything is OK before actually migrating the
data to the translations tables.

spec/lib/tasks/globalize_spec.rb

@@ -11,6 +11,7 @@ describe "Globalize tasks" do
     end
 
     let :run_rake_task do
+      Rake::Task["globalize:simulate_migrate_data"].reenable
       Rake::Task["globalize:migrate_data"].reenable
       Rake.application.invoke_task "globalize:migrate_data"
     end
@@ -115,5 +116,34 @@ describe "Globalize tasks" do
         expect(page.send(:"title_#{I18n.locale}")).to eq("In English")
       end
     end
+
+    context "Invalid data" do
+      let!(:valid_process) do
+        create(:legislation_process).tap do |process|
+          process.translations.delete_all
+          process.update_column(:title, "Title")
+          process.reload
+        end
+      end
+
+      let!(:invalid_process) do
+        create(:legislation_process).tap do |process|
+          process.translations.delete_all
+          process.update_column(:title, "")
+          process.reload
+        end
+      end
+
+      it "simulates the task and aborts without creating any translations" do
+        expect(valid_process).to be_valid
+        expect(invalid_process).not_to be_valid
+
+        expect { run_rake_task }.to raise_exception("Simulation failed!")
+
+        expect(Legislation::Process::Translation.count).to eq 0
+        expect(valid_process.reload.title).to eq "Title"
+        expect(invalid_process.reload.title).to eq ""
+      end
+    end
   end
 end