const int MAXN=505;
char buf[MAXN][MAXN];
int main()
{
	int T=read_int();
	while(T--){
		int n=read_int(),m=read_int();
		_for(i,0,n)scanf("%s",buf[i]);
		int s1,s2;
		if(n%3==1){
			s1=0;
			s2=2;
		}
		else{
			s1=1;
			s2=3;
		}
		for(int i=s1;i<n;i+=3)_for(j,0,m)buf[i][j]='X';
		for(int i=s2;i<n;i+=3){
			bool flag=false;
			_for(j,0,m){
				if(buf[i-1][j]=='X'||buf[i][j]=='X'){
					buf[i-1][j]=buf[i][j]='X';
					flag=true;
					break;
				}
			}
			if(!flag)
			buf[i-1][0]=buf[i][0]='X';
		}
		_for(i,0,n)puts(buf[i]);
	}
	return 0;
}