Method ReadAt

cpp/src/arrow/io/test_common.cc:134–137

  bool supports_zero_copy() const override { return delegate_->supports_zero_copy(); }
  Result<int64_t> GetSize() override { return delegate_->GetSize(); }
  Result<int64_t> ReadAt(int64_t position, int64_t nbytes, void* out) override {
    SaveReadRange(position, nbytes);
    return delegate_->ReadAt(position, nbytes, out);
  }
  Result<std::shared_ptr<Buffer>> ReadAt(int64_t position, int64_t nbytes) override {
    return ReadAt(position, nbytes, /*allow_short_read=*/true);
  }