public:
  OutEdgeMatcher(::testing::Matcher<const Node*> src_matcher, int src_oidx)
      : src_matcher_(std::move(src_matcher)), src_oidx_(src_oidx) {}

  bool MatchAndExplain(
      OutEdge out_edge,
      ::testing::MatchResultListener* listener) const override {
    ::testing::StringMatchResultListener inner_listener;
    if (!src_matcher_.MatchAndExplain(out_edge.first, &inner_listener)) {