Made ruby per-rpc creds interop use auth plugin API

src/ruby/lib/grpc.rb

@@ -1,4 +1,4 @@
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -27,7 +27,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-ssl_roots_path = File.expand_path('../../../etc/roots.pem', __FILE__)
+ssl_roots_path = File.expand_path('../../../../etc/roots.pem', __FILE__)
 unless ENV['GRPC_DEFAULT_SSL_ROOTS_FILE_PATH']
   ENV['GRPC_DEFAULT_SSL_ROOTS_FILE_PATH'] = ssl_roots_path
 end

src/ruby/pb/test/client.rb

@@ -1,6 +1,6 @@
 #!/usr/bin/env ruby
 
-# Copyright 2015, Google Inc.
+# Copyright 2015-2016, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -266,16 +266,20 @@ class NamedTests
 
   def per_rpc_creds
     auth_creds = Google::Auth.get_application_default(@args.oauth_scope)
+    update_metadata = proc do |md|
       kw = auth_creds.updater_proc.call({})
 
-    # TODO(jtattermusch): downcase the metadata keys here to make sure
+      # TODO(mlumish): downcase the metadata keys here to make sure
       # they are not rejected by C core. This is a hotfix that should
       # be addressed by introducing auto-downcasing logic.
-    kw = Hash[ kw.each_pair.map { |k, v|  [k.downcase, v] }]
+      Hash[ kw.each_pair.map { |k, v|  [k.downcase, v] }]
+    end
+
+    call_creds = GRPC::Core::CallCredentials.new(update_metadata)
 
     resp = perform_large_unary(fill_username: true,
                                fill_oauth_scope: true,
-                               **kw)
+                               credentials: call_creds)
     json_key = File.read(ENV[AUTH_ENV])
     wanted_email = MultiJson.load(json_key)['client_email']
     assert("#{__callee__}: bad username") { wanted_email == resp.username }