#include<bits/stdc++.h>
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fd(i,a,b) for(int i=a;i>=b;i--)
using namespace std;

typedef long long LL;
typedef pair<int,int> pr;

const int maxn=505;

int n,m;
char mp[maxn][maxn];

int T;
int main()
{
	scanf("%d",&T);
	while (T--)
	{
		scanf("%d %d",&n,&m);
		fo(i,1,n) scanf("%s",mp[i]+1);
		
		fo(i,1,n) if (i%3==1)
			fo(j,1,m) mp[i][j]='X';
		fo(i,1,n) if (i%3==1 && i+3<=n)
		{
			bool pd=0;
			fo(j,1,m) if (mp[i+1][j]=='X')
			{
				mp[i+2][j]='X';
				pd=1;
				break;
			}
			if (pd) continue;
			fo(j,1,m) if (mp[i+2][j]=='X')
			{
				mp[i+1][j]='X';
				pd=1;
				break;
			}
			if (pd) continue;
			mp[i+1][1]=mp[i+2][1]='X';
		}
		if (n%3==0)
		{
			fo(j,1,m) if (mp[n][j]=='X') mp[n-1][j]='X';
		}
		
		fo(i,1,n) printf("%s\n",mp[i]+1);
	}
}