#include <bits/stdc++.h>
using namespace std;
const int maxn = 1005;
#define int long long
char str[maxn];
int dp[maxn],n,cost[2],c;

signed main()
{
    signed T; scanf("%d",&T);
    while(T--) 
    {
        scanf("%lld%lld%lld%lld",&n,&cost[0],&cost[1],&c);
        scanf("%s",str+1);
        for(int i=1;i<=n;++i)
            dp[i] = dp[i-1] + min(cost[str[i] - '0'],c + cost[!(str[i] - '0')]);
        cout << dp[n] << endl;
    }
    return 0;
}