#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e18;
const long long mod = 1e9 + 7;
const long long N = 2e5 + 1;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
long long power(long long a, long long b = mod - 2) {
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
    b >>= 1;
  }
  return res;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  long long t;
  cin >> t;
  ;
  while (t--) {
    long long n, a, b, h;
    cin >> n >> a >> b >> h;
    string s;
    cin >> s;
    ;
    long long sum = 0;
    for (char c : s)
      if (c == '0')
        sum += min(a, b + h);
      else
        sum += min(b, a + h);
    cout << sum << '\n';
    ;
  }
}
