Method MatchAndExplain

common/value_testing.cc:147–159

      : matcher_(std::move(matcher)) {}

  bool MatchAndExplain(const Value& v,
                       testing::MatchResultListener* listener) const override {
    if (!v.IsOptional()) {
      *listener << "wanted OptionalValue, got " << ValueKindToString(v.kind());
      return false;
    }
    const auto& optional_value = v.GetOptional();
    if (!optional_value.HasValue()) {
      *listener << "OptionalValue is not engaged";
      return false;
    }
    return matcher_.MatchAndExplain(optional_value.Value(), listener);
  }

  void DescribeTo(std::ostream* os) const override {
    *os << "is OptionalValue that is engaged with value whose ";