Update lib/rack/test/utils.rb

Co-authored-by: Matt Palmer <[email protected]>

Author: jdufresne

lib/rack/test/utils.rb

@@ -22,8 +22,11 @@ def build_nested_query(value, prefix = nil)
           when nil
             escape(prefix)
           else
-            raise ArgumentError, "value must be a Hash" if prefix.nil?
-            "#{escape(prefix)}=#{escape(value)}"
+            if prefix.nil?
+              raise ArgumentError, "value must be a Hash, Array, or nil"
+            else
+              "#{escape(prefix)}=#{escape(value)}"
+            end
           end
         end
       end