#include<iostream>
#include<algorithm>
#include<string>

using namespace std;

int q[1010];

int main()
{
    int n,a,b,c;
    string s;
    int t;
    cin>>t;
    while(t--)
    {
        int sum = 0,ans = 0;
        cin>>n>>a>>b>>c;
        cin>>s;
        for(int i = 0;i < s.size();i ++)
            if(s[i] == '0')
                sum++;

        if(a <= b)
        {
            ans = a*sum;
            ans += min(b*(n - sum),(a + c)*(n - sum));
        }
        else 
        {
            ans = b*(n - sum);
            ans += min(a*sum,(b + c)*sum);
        }
        cout<<ans<<endl;
    }
    return 0;
}