#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n, c0, c1, h;
  cin >> n >> c0 >> c1 >> h;
  int one = 0;
  char c;
  for (int i = 0; i < n; i++) {
    cin >> c;
    if (c - '0') one++;
  }
  int zero = n - one;
  if (c0 > c1) {
    swap(c0, c1);
    swap(zero, one);
  }
  int diff = c1 - c0;
  long long cost = c0 * zero;
  if (h < diff) {
    cost += (c0 * one + one * h);
  } else {
    cost += (c1 * one);
  }
  cout << cost << "\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int tc = 1;
  cin >> tc;
  while (tc--) solve();
  return 0;
}
