#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e9 + 5;
const long long N = 205;
void solve();
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  cout << fixed << setprecision(10);
  long long _ = 1;
  cin >> _;
  while (_--) solve();
  return 0;
}
void solve() {
  long long n, a, b, x;
  cin >> n >> a >> b >> x;
  string s;
  cin >> s;
  long long cn = 0;
  for (long long i = 0; i < n; i++) {
    if (s[i] == '0') cn++;
  }
  long long cnt = n - cn;
  long long total = cn * a + cnt * b;
  long long tot = cn * a;
  if (a <= b + x) {
    tot += cnt * (a + x);
  } else {
    tot += cnt * b;
  }
  total = min(total, tot);
  tot = 0;
  tot = cnt * b;
  if (b <= a + x) {
    tot += cn * (b + x);
  } else {
    tot += cn * a;
  }
  total = min(total, tot);
  cout << total << "\n";
}
