Actually allow top level params to be ParamsArray.

Because of some idiosyncratic behavior in Request#process_url_params, we
would previously only handle params that were Hash objects. This is
really confusing behavior that stems from mixing options and headers.
Unfortunately we won't be able to clean that up until rest-client 3.0,
but at least allow ParamsArray or Hash for now.

lib/restclient/request.rb

@@ -224,18 +224,38 @@ module RestClient
     end
 
     # Extract the query parameters and append them to the url
-    def process_url_params url, headers
-      url_params = {}
+    #
+    # Look through the headers hash for a :params option (case-insensitive,
+    # may be string or symbol). If present and the value is a Hash or
+    # RestClient::ParamsArray, *delete* the key/value pair from the headers
+    # hash and encode the value into a query string. Append this query string
+    # to the URL and return the resulting URL.
+    #
+    # @param [String] url
+    # @param [Hash] headers An options/headers hash to process. Mutation
+    #   warning: the params key may be removed if present!
+    #
+    # @return [String] resulting url with query string
+    #
+    def process_url_params(url, headers)
+      url_params = nil
+
+      # find and extract/remove "params" key if the value is a Hash/ParamsArray
       headers.delete_if do |key, value|
-        if 'params' == key.to_s.downcase && value.is_a?(Hash)
-          url_params.merge! value
+        if key.to_s.downcase == 'params' &&
+            (value.is_a?(Hash) || value.is_a?(RestClient::ParamsArray))
+          if url_params
+            raise ArgumentError.new("Multiple 'params' options passed")
+          end
+          url_params = value
           true
         else
           false
         end
       end
 
-      unless url_params.empty?
+      # build resulting URL with query string
+      if url_params && !url_params.empty?
         query_string = RestClient::Utils.encode_query_string(url_params)
 
         if url.include?('?')

spec/unit/request_spec.rb

@@ -1173,5 +1173,11 @@ describe RestClient::Request, :include_helpers do
                    '&nested[key+%2B+escaped]=value+%2B+escaped&nested[other]' \
                    '&nested[arr][]=1&nested[arr][]=2'
     end
+
+    it 'should handle ParamsArray objects' do
+      @request.process_url_params('https://example.com/',
+        params: RestClient::ParamsArray.new([[:foo, 1], [:foo, 2]])
+      ).should eq 'https://example.com/?foo=1&foo=2'
+    end
   end
 end