#include <bits/stdc++.h>
int dr[] = {2, 2, -2, -2, 1, -1, 1, -1};
int dc[] = {1, -1, 1, -1, 2, 2, -2, -2};
int dr1[] = {0, 0, 1, 1, 1, -1, -1, -1};
int dc1[] = {1, -1, 1, 0, -1, 0, 1, -1};
int dr2[] = {0, 0, 1, -1};
int dc2[] = {1, -1, 0, 0};
using namespace std;
long long a[500004], b[500004];
int main() {
  long long n, m, i, j, tc, w, c0, c1, h;
  cin >> tc;
  while (tc--) {
    cin >> n >> c0 >> c1 >> h;
    string t;
    cin >> t;
    long long ans = 0;
    for (i = 0; i < t.size(); i++) {
      if (t[i] == '0') {
        ans += min(c0, c1 + h);
      } else {
        ans += min(c1, c0 + h);
      }
    }
    cout << ans << endl;
  }
  return 0;
}
