//by dp王子
#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define mem(x) memset(x,0,sizeof(x))
//const ll inf=1000000000000000000; 

const int N=100001;
int n,m,T; 

inline int read()
{
	char C=getchar();
	int F=1,ANS=0;
	while (C<'0'||C>'9')
	{
		if (C=='-') F=-1;
		C=getchar();
	}
	while (C>='0'&&C<='9')
	{
		ANS=ANS*10+C-'0';
		C=getchar();
	}
	return F*ANS;
} 
char a[505][505];
void work()
{
	n=read(),m=read();
	for (int i=1;i<=n;i++)
	{
		for (int j=1;j<=m;j++) cin >> a[i][j];
	}
	int u=0;
	if (n%3==0) u=1;
		for (int i=1;i<=n;i++)
		{
			if (i%3==u%3) continue;
			bool flag=0;
			for (int j=1;j<=m;j++)
			{
				if (i%3==(u+1)%3) a[i][j]='X';
				else
				{
					if (i!=n&&(a[i][j]=='X'||a[i+1][j]=='X')&&flag==0) 
					{
						flag=1;
						a[i][j]='X',a[i+1][j]='X';
					}
				}
			}
			if (i%3==(u+2)%3&&flag==0)
			{
				a[i][1]=a[i+1][1]='X';
			}
		}	
	return;
}

int main()
{
	T=read();
	while (T--)
	{
		work();
		for (int i=1;i<=n;i++)
		{
			for (int j=1;j<=m;j++)
			{
				cout << a[i][j] ;
			}
			cout << endl;
		}
	}
	return 0;
}