Forgot to add the test file.

test/build/protobuf.cc

+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/descriptor.pb.h>
+
+bool protobuf_test(const google::protobuf::MethodDescriptor *method) {
+  return method->client_streaming() || method->server_streaming();
+}
+
+int main() {
+  return 0;
+}