Fixed issue with header/options ambiguity.

lib/google/api_client.rb

@@ -533,14 +533,10 @@ module Google
     #   )
     def execute(*params)
       # This block of code allows us to accept multiple parameter passing
-      # styles, and maintaining backwards compatibility.
-      if params.last.respond_to?(:to_hash) && params.size != 2
-        # Hash options are tricky. If we get two arguments, it's ambiguous
-        # whether to treat them as API parameters or Hash options, but since
-        # it's rare to need to pass in options, we must assume that the
-        # developer wanted to pass API parameters. Prefer using named
-        # parameters to avoid this issue. Unnamed parameters should be
-        # considered syntactic sugar.
+      # styles, and maintaining some backwards compatibility.
+      #
+      # Note: I'm extremely tempted to deprecate this style of execute call.
+      if params.last.respond_to?(:to_hash) && params.size == 1
         options = params.pop
       else
         options = {}

spec/google/api_client/discovery_spec.rb

@@ -14,6 +14,7 @@
 
 require 'spec_helper'
 
+require 'json'
 require 'signet/oauth_1/client'
 require 'httpadapter/adapters/net_http'
 
@@ -238,6 +239,19 @@ describe Google::APIClient do
         )
       end).should raise_error(Google::APIClient::ClientError)
     end
+
+    it 'should correctly handle unnamed parameters' do
+      @client.authorization = :oauth_2
+      @client.authorization.access_token = '12345'
+      result = @client.execute(
+        @prediction.training.insert,
+        {},
+        JSON.generate({"id" => "bucket/object"}),
+        {'Content-Type' => 'application/json'}
+      )
+      method, uri, headers, body = result.request
+      Hash[headers]['Content-Type'].should == 'application/json'
+    end
   end
 
   describe 'with the buzz API' do