fix: add verify_contents spec helper

Author: TheMeier

spec/support/spec/verify_contents.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+def verify_contents(subject, title, expected_lines)
+  content = subject.resource('file', title).send(:parameters)[:content]
+  expect(content.split("\n") & expected_lines).to match_array expected_lines.uniq
+end