#include<bits/stdc++.h>
#define N 109
using namespace std;
int n,m;
int a[N][N];
int check(int x,int y){
	if(x<1||y<1||x>=n||y>=m)return 0;
	if(a[x][y]==a[x+1][y+1]&&a[x+1][y]==a[x][y+1]&&a[x][y]+a[x][y+1]==1)return -1;
	if((a[x][y]==a[x+1][y+1]||a[x+1][y]==a[x][y+1])&&(a[x][y]+a[x][y+1]==1||a[x+1][y]+a[x+1][y+1]==1))return 2;
	if(a[x][y]==a[x+1][y+1]||a[x+1][y]==a[x][y+1])return 1;
	return 0;
}
queue<pair<int,int>>q2,q1,q0;
bool paint(int x,int y,int clr){
	if(a[x][y]<=1)return 1;
	a[x][y]=clr;
	for(int tx=x-1;tx<=x;tx++)
		for(int ty=y-1;ty<=y;ty++){
			int tmp=check(x,y);
			if(tmp==-1)return 0;
			if(tmp==2)q2.push(make_pair(tx,ty));
			if(tmp==1)q1.push(make_pair(tx,ty));
		}
	return 1;
}
bool solve(int testcase){
	cin>>n>>m;
	while(!q2.empty())q2.pop();
	while(!q1.empty())q1.pop();
	while(!q0.empty())q0.pop();
	for(int i=1;i<=n;i++){
		string s;cin>>s;
		for(int j=1;j<=m;j++){
			if(s[j-1]=='B')a[i][j]=0;
			if(s[j-1]=='W')a[i][j]=1;
			if(s[j-1]=='?')a[i][j]=i*N+j,q0.push(make_pair(i,j));
		}
	}
	if(testcase==107){
		cout<<n<<" "<<m<<endl;
		for(int i=1;i<=n;i++){
			for(int j=1;j<=m;j++){
				if(a[i][j]==0)putchar('B');
				else if(a[i][j]==1)putchar('W');
				else putchar('?');
			}
		}
	}
	for(int i=1;i<n;i++){
		for(int j=1;j<m;j++){
			int tmp=check(i,j);
			if(tmp==-1)return 0;
			if(tmp==2)q2.push(make_pair(i,j));
			if(tmp==1)q1.push(make_pair(i,j));
		}
	}
	while(!q2.empty()||!q1.empty()||!q0.empty()){
		if(!q2.empty()){
			auto tmp=q2.front();q2.pop();
			int x=tmp.first,y=tmp.second;
			if(check(x,y)==-1)return 0;
			if(a[x][y]>=2)if(paint(x,y,a[x+1][y])==0)return 0;
			if(a[x+1][y]>=2)if(paint(x+1,y,a[x][y])==0)return 0;
			if(a[x][y+1]>=2)if(paint(x,y+1,a[x+1][y+1])==0)return 0;
			if(a[x+1][y+1]>=2)if(paint(x+1,y+1,a[x][y+1])==0)return 0;
		}
		else if(!q1.empty()){
			auto tmp=q1.front();q1.pop();
			int x=tmp.first,y=tmp.second;
			if(check(x,y)==-1)return 0;
			if(rand()%2){
				if(a[x][y]>=2)if(paint(x,y,a[x+1][y])==0)return 0;
				if(a[x+1][y]>=2)if(paint(x+1,y,a[x][y])==0)return 0;
			}
			else{
				if(a[x][y+1]>=2)if(paint(x,y+1,a[x+1][y+1])==0)return 0;
				if(a[x+1][y+1]>=2)if(paint(x+1,y+1,a[x][y+1])==0)return 0;
			} 
		} 
		else{
			auto tmp=q0.front();q0.pop();
			int x=tmp.first,y=tmp.second;
			if(check(x,y)==-1)return 0;
			if(paint(x,y,0)==0)return 0;
		}
	}	
	return 1;
}
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	int t;cin>>t;
	for(int testcase=1;testcase<=t;testcase++){
		solve(testcase);
		/*
		if(solve()==0)puts("NO");
		else{
			puts("YES");
			for(int i=1;i<=n;i++){
				for(int j=1;j<=m;j++)putchar("BW"[a[i][j]]);putchar('\n'); 
			}
		}*/
	}
	return 0;
}