#include<bits/stdc++.h>

using namespace std;

const int maxn = ;

char str[maxn][maxn];

int cntx[maxn], cnty[maxn],x[maxn],y[maxn];

int main(void){

    int T,n,m;scanf("%d",&T)；

    while(T --){

        scanf("%d%d",&n,&m);

        int tot = ;

        memset(cntx, , sizeof(cntx));

        memset(cnty, , sizeof(cnty));

        memset(x, -, sizeof(x));

        memset(y, -, sizeof(y));

        for(int i = ; i < n; i ++){

            scanf("%s", str[i]);

            for(int j = ; j < m; j ++){

                if(str[i][j] == '#'){

                    cntx[i] ++;cnty[j] ++;

                    tot ++;

                }else{

                    x[i] = j;y[j] = i;

                }

            }

        }

        long long ans = ;

        for(int i = ; i < n; i ++)

            for(int j = i + ; j < n; j ++)

                ans += (long long)(j - i) * cntx[i] * cntx[j] * ;

        for(int i = ; i < m; i ++)

            for(int j = i + ; j < m; j ++)

                ans += (long long)(j - i) * cnty[i] * cnty[j] * ;

        int cnt = ;

        for(int i = ; i < n; i ++){

            if(x[i] == -) cnt = ;

            else if(i ==  || x[i] <= x[i - ]) cnt = x[i];

            else cnt += x[i];

            if(x[i] != -)

                ans += 4LL * cnt * (m - x[i] - );

        }

        cnt = ;

        for(int i = ; i < n; i ++){

            if((i == )||(x[i] > x[i - ])||(x[i] == -)) cnt = m - x[i] - ;

            else cnt += m - x[i] - ;

            if(x[i] >= )

                ans += 4LL * (cnt - m + x[i] + ) * (x[i]>?x[i]:);

        }

        cnt = ;

        for(int i = ; i < m; i ++){

            if(y[i] == -) cnt = ;

            else if(i ==  || y[i] <= y[i - ]) cnt = y[i];

            else cnt += y[i];

            ans += 4LL * cnt * (n - y[i] - );

        }

        cnt = ;

        for(int i = ; i < m; i ++){

            if((i == )||(y[i] > y[i - ])||(y[i] == -)) cnt = n - y[i] - ;

            else cnt += n - y[i] - ;

            if(y[i] >= )

                ans += 4LL * (cnt - n + y[i] + ) * (y[i]>?y[i]:);

        }

        printf("%.4lf\n",(double)ans/tot/tot);

    }

    return ;

}