Fix include_module matcher

spec/support/matchers.rb

@@ -33,7 +33,11 @@ RSpec::Matchers.define :include_module do |expected|
     described_class.included_modules.include?(expected)
   end
 
-  failure_message_for_should do
+  description do
+    "include the #{expected} module"
+  end
+
+  failure_message do
     "expected #{described_class} to include the #{expected} module"
   end
 end