#include<iostream>
#include<cstdio>
#include<vector>

using namespace std;

#define MAXN 50000+5

int T, M, N, K;
int seenid = 0;

vector<int> comps;

int di[] = {1, -1, 0, 0};
int dj[] = {0, 0, -1, 1};

int seen[MAXN];
string maze[MAXN];

bool ok(int i, int j) {
    return i >= 0 && i < M && j >= 0 && j < N && maze[i][j] != '#' && seen[ N*i + j ] != seenid;
}

int dfs(int i, int j) {
    seen[ N*i + j ] = seenid;
    int cnt = 1;
    for (int k = 0; k < 4; k++) {
        int ni = i + di[k], nj = j + dj[k];
        if ( !ok(ni, nj) )  continue;
        cnt += dfs(ni, nj);
    }
    return cnt;
}

#ifdef BRUTE

double dp[1<<18];
int vis[1<<18];

double E(int mask) {
    if (vis[mask] == seenid)  return dp[mask];
    vis[mask] = seenid;
    double sum = 0, ans = 0;
    for (int i = 0; i < K; i++) {
        if ((1<<i) & mask)  continue;
        sum += comps[i];
    }
    for (int i = 0; i < K; i++) {
        if ((1<<i) & mask)  continue;
        if (i == 0) ans += (comps[i] / sum);
        else ans += (comps[i] / sum) * (1 + E(mask ^ (1<<i)));
    }
    return dp[mask] = ans;
}

#endif

int main() {
    scanf("%d", &T);
    while (T--) {
        seenid++;
        comps.clear();
        scanf("%d%d", &M, &N);
        for (int i = 0; i < M; i++) {
            cin >> maze[i];
        }
        for (int i = 0; i < M; i++) {
            for (int j = 0; j < N; j++) {
                if ( !ok(i, j) ) continue;
                comps.push_back( dfs(i, j) );
            }
        }
        K = (int)comps.size();

        #ifdef BRUTE
        printf("%.10f\n", E(0));
        #endif

        #ifndef BRUTE
        long double ans = 1.0;
        for (int i = 1; i < K; i++) {
            ans += (comps[i] * (long double)1.0) / (comps[i] + comps[0]);
        }
        printf("%.10Lf\n", ans);
        #endif
    }
}