#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
const int MOD = 1e9 + 7;
const long double PI = acosl(-1.0);
const long double EPS = 1e-9;
void solve() {
  int n, a, b, h;
  cin >> n >> a >> b >> h;
  string s;
  cin >> s;
  int ans = 0;
  for (int i = 0; i < n; ++i) {
    if (s[i] == '1') {
      ans += min(a + h, b);
    } else {
      ans += min(a, b + h);
    }
  }
  cout << ans << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int T = 1;
  cin >> T;
  while (T--) {
    solve();
  }
}
