Update generator to use batchPath instead of hardcoded path

spec/fixtures/files/test_api.json

@@ -7,6 +7,7 @@
   "basePath": "/test/",
   "rootUrl": "https://www.googleapis.com/",
   "servicePath": "test/v1/",
+  "batchPath": "batch/test/v1",
   "rpcPath": "/rpc",
   "auth": {
     "oauth2": {

spec/google/apis/generator/generator_spec.rb

@@ -30,6 +30,7 @@ RSpec.describe Google::Apis::Generator do
       puts generator.dump_api_names
       tempdir = Dir.mktmpdir
       generated_files.each do |key, content|
+        puts content
         path = File.join(tempdir, key)
         FileUtils.mkdir_p(File.dirname(path))
         File.open(path, 'w') do |f|
@@ -47,6 +48,10 @@ RSpec.describe Google::Apis::Generator do
         expect(service.root_url.to_s).to eql('https://www.googleapis.com/')
       end
 
+      it 'should set the batch path' do
+        expect(service.batch_path).to eql('batch/test/v1')
+      end
+
       it 'should define global methods from discovery' do
         expect(service.method(:query)).to_not be_nil
       end