Fix CI failure (#129)

spec/spec_helper.rb

@@ -26,6 +26,7 @@ def method_from_description(example)
   end
 
   def args_for_method(method)
+    return [] if method.to_s == 'spop'
     method_arity = @redises.real.method(method).arity
     if method_arity < 0 # -1 comes from def foo(*args)
       [1, 2] # probably good enough