#include <bits/stdc++.h>
using namespace std;
const unsigned mod = 998244353;
const unsigned _mod = 1e9 + 7;
const long long infi = 0x3f3f3f3f3f3f3f3fll;
const int inf = 0x3f3f3f3f;
long long ksm(long long x, long long y) {
  long long ret = 1;
  while (y) {
    if (y & 1ll) ret = ret * x % mod;
    y >>= 1ll;
    x = x * x % mod;
  }
  return ret;
}
long long qpow(long long x, long long y, long long m) {
  long long ret = 1;
  while (y) {
    if (y & 1ll) ret = ret * x % m;
    y >>= 1ll;
    x = x * x % m;
  }
  return ret;
}
long long _gcd(long long x, long long y) { return y ? _gcd(y, x % y) : x; }
long long read() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (ch > '9' || ch < '0') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
int n, c0, c1, h;
string s;
int main() {
  int T;
  cin >> T;
  while (T--) {
    cin >> n >> c0 >> c1 >> h >> s;
    int cnt1 = 0, cnt2 = 0;
    for (register int i = 0; i <= n - 1; ++i) {
      if (s[i] == '0')
        cnt1++;
      else
        cnt2++;
    }
    cout << cnt1 * min(c0, c1 + h) + cnt2 * min(c1, c0 + h) << '\n';
  }
  return 0;
}
