#include <bits/stdc++.h>
using namespace std;
long long n, c0, c1, h, i;
string s;
void solve() {
  cin >> n >> c0 >> c1 >> h >> s;
  int sol = 0;
  for (i = 0; i < n; i++) {
    if (s[i] == '0') {
      sol += min(c0, h + c1);
    } else {
      sol += min(c1, h + c0);
    }
  }
  cout << sol << endl;
}
int main(int argc, const char* argv[]) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long int t;
  cin >> t;
  while (t--) {
    solve();
  }
  return 0;
};
