#include <bits/stdc++.h>
using namespace std;
int dx[] = {0, 0, 1, -1, -1, -1, 1, 1};
int dy[] = {1, -1, 0, 0, -1, 1, 1, -1};
template <class T>
inline T bitOn(T n, T pos) {
  return n | ((T)1 << pos);
}
template <class T>
inline T bitOff(T n, T pos) {
  return n & ~((T)1 << pos);
}
template <class T>
inline T isOn(T n, T pos) {
  return (bool)(n & ((T)1 << pos));
}
template <class T>
inline T lcm(T a, T b) {
  return (a / __gcd(a, b)) * b;
}
template <class T>
istream& operator>>(istream& is, vector<T>& input) {
  for (T& in : input) is >> in;
  return is;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& input) {
  bool isFirst = true;
  for (const T& out : input) {
    if (isFirst) {
      os << out;
      isFirst = false;
    } else
      os << " " << out;
  }
  return os;
}
void solve() {
  int n, c0, c1, h;
  cin >> n >> c0 >> c1 >> h;
  string s;
  cin >> s;
  int one = count(s.begin(), s.end(), '1');
  int zero = count(s.begin(), s.end(), '0');
  if (abs(c0 - c1) >= h) {
    if (c0 > c1) {
      cout << c1 * one + (c1 + h) * zero << '\n';
    } else {
      cout << c0 * zero + (c0 + h) * one << '\n';
    }
  } else {
    cout << c0 * zero + c1 * one << '\n';
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  cout.setf(ios::fixed);
  cout.precision(10);
  int tc = 1;
  cin >> tc;
  while (tc--) {
    solve();
  }
  return 0;
}
