#include<bits/stdc++.h>
#define ll long long
#define LL inline ll
#define I inline int 
#define V inline void
#define FOR(i,a,b) for(int i=(a),i##i=(b);i<=i##i;++i)
#define ROF(i,a,b) for(int i=(a),i##i=(b);i>=i##i;--i)
// #define gc (_ft==_fs&&(_ft=(_fs=buf)+fread(buf,1,1<<20,stdin),_ft==_fs))?0:*_fs++
#define gc getchar()
using namespace std;
const int N=110,M=1e5,inf=998244353;
char buf[1<<20],*_fs,*_ft;
LL read(){
	ll w=0,p=0; char ch=gc;
	while(!isdigit(ch)) w=ch=='-',ch=gc;
	while(isdigit(ch)) p=p*10+ch-'0',ch=gc;
	return w?-p:p;
}
int n,m;
char ch[N][N];
V sol(){
    FOR(i,1,n) FOR(j,1,m) if(ch[i][j]=='?'){
        int x=0,y=0;
        if(ch[i][j+1]=='B') x++;
        if(ch[i][j-1]=='B') x++;
        if(ch[i+1][j]=='B') x++;
        if(ch[i-1][j]=='B') x++;

        if(ch[i][j+1]=='W') y++;
        if(ch[i][j-1]=='W') y++;
        if(ch[i+1][j]=='W') y++;
        if(ch[i-1][j]=='W') y++;       

        if(x>=y) ch[i][j]='B';
        else ch[i][j]='W';
    }

    return ;
}
I ck(){
    FOR(i,1,n) FOR(j,1,n) {
        if(ch[i-1][j-1]=='W'&&ch[i-1][j]=='B'&&ch[i][j-1]=='B'&&ch[i][j]=='W') return 0;
        if(ch[i-1][j-1]=='B'&&ch[i-1][j]=='W'&&ch[i][j-1]=='W'&&ch[i][j]=='B') return 0;
    }
    return 1;
} 
int main(){
    int T=read();
    while(T--){
        n=read(),m=read();
        FOR(i,1,n) scanf("%s",ch[i]+1);
        sol();
        if(!ck()) cout<<"NO"<<'\n';
        else {
            cout<<"YES"<<'\n';
            FOR(i,1,n) {
                FOR(j,1,m) cout<<ch[i][j];
                cout<<'\n';
            }
        }
    }


    return 0;
}
/*
3
2 2
??
??
3 3
BW?
W?B
?BW
3 3
BW?
W?W
?W?
*/