[era_restore] add some cucumber tests

features/step_definitions/era_steps.rb

@@ -14,3 +14,18 @@ end
 Then /^era_usage to stderr$/ do
   assert_partial_output(ERA_USAGE, all_stderr)
 end
+
+When(/^I run era_restore with (.*?)$/) do |opts|
+  run_simple("era_restore #{opts}", false)
+end
+
+Given(/^a small era xml file$/) do
+  in_current_dir do
+    system("era_xml create --nr-blocks 100 --nr-writesets 2 --current-era 1000 > #{xml_file}")
+  end
+end
+
+Then(/^the metadata should be valid$/) do
+  run_simple("era_check #{dev_file}", true)
+end
+