#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<random>
#include<cassert>
#define N 100
#define M 1000000
using namespace std;
mt19937 RAND(random_device{}());
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
struct reads
{
	int x,y;
};
reads tong[M+1];
int T,n,m,length;
char c[N+1][N+1];
bool op;
void solve(int x,int y,int opt)
{
	if (op) return;
	int sx,sy;
	if ((c[x][y]=='B')+(c[x+1][y]=='W')+(c[x][y+1]=='W')+(c[x+1][y+1]=='B')==4)
	{
		op=1;
		return;
	}
	if ((c[x][y]=='W')+(c[x+1][y]=='B')+(c[x][y+1]=='B')+(c[x+1][y+1]=='W')==4)
	{
		op=1;
		return;
	}
	if ((c[x][y]=='B')+(c[x+1][y]=='W')+(c[x][y+1]=='W')+(c[x+1][y+1]=='B')==3)
	{
		if (c[x][y]=='?') c[x][y]='W',sx=x,sy=y;
		else if (c[x+1][y]=='?') c[x+1][y]='B',sx=x+1,sy=y;
		else if (c[x][y+1]=='?') c[x][y+1]='B',sx=x,sy=y+1;
		else if (c[x+1][y+1]=='?') c[x+1][y+1]='W',sx=x+1,sy=y+1;
		else return;
		if (opt) tong[++length]=(reads){sx,sy};
		if (sx!=1&&sy!=n) solve(sx-1,sy,opt);
		if (sx!=n&&sy!=1) solve(sx,sy-1,opt);
		if (sx!=1&&sy!=1) solve(sx-1,sy-1,opt);
	}
	if ((c[x][y]=='W')+(c[x+1][y]=='B')+(c[x][y+1]=='B')+(c[x+1][y+1]=='W')==3)
	{
		if (c[x][y]=='?') c[x][y]='B',sx=x,sy=y;
		else if (c[x+1][y]=='?') c[x+1][y]='W',sx=x+1,sy=y;
		else if (c[x][y+1]=='?') c[x][y+1]='W',sx=x,sy=y+1;
		else if (c[x+1][y+1]=='?') c[x+1][y+1]='B',sx=x+1,sy=y+1;
		else return;
		if (opt) tong[++length]=(reads){sx,sy};
		if (sx!=1&&sy!=n) solve(sx-1,sy,opt);
		if (sx!=n&&sy!=1) solve(sx,sy-1,opt);
		if (sx!=1&&sy!=1) solve(sx-1,sy-1,opt);
	}
	return;
}
int main()
{
	char cs;
	T=read();
	while (T--)
	{
		n=read(),m=read(),op=0;
		for (int i=1;i<=n;++i)
			for (int j=1;j<=m;++j)
				cin>>c[i][j];
		for (int i=1;i<=n-1;++i)
			for (int j=1;j<=m-1;++j)
				solve(i,j,0);
		if (op) puts("NO");
		else
		{
			for (int i=1;i<=n;++i)
				for (int j=1;j<=m;++j)
					if (c[i][j]=='?')
					{
						cs=(RAND()&1)?'W':'B',c[i][j]=cs,length=0;
						if (i!=n&&j!=m) solve(i,j,1);
						if (i!=1&&j!=m) solve(i-1,j,1);
						if (i!=n&&j!=1) solve(i,j-1,1);
						if (i!=1&&j!=1) solve(i-1,j-1,1);
						if (op)
						{
							for (int k=1;k<=length;++k) c[tong[k].x][tong[k].y]='?';
						    c[i][j]=cs^'W'^'B',op=length=0;
							if (i!=n&&j!=m) solve(i,j,1);
							if (i!=1&&j!=m) solve(i-1,j,1);
							if (i!=n&&j!=1) solve(i,j-1,1);
							if (i!=1&&j!=1) solve(i-1,j-1,1);
						}
					}
			puts("YES");
			for (int i=1;i<=n;++i)
			{
				for (int j=1;j<=m;++j) printf("%c",c[i][j]);
				puts("");
			}
		}
	}
	return 0;
}