import java.io.*;
import java.lang.reflect.Array;
import java.util.*;

public class D {

    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        int q = sc.nextInt();
        while(q-->0){
            int n = sc.nextInt();
            int m = sc.nextInt();
            int[][] arr = new int[n][m];
            int g = 0;
            for(int i=0;i<n;i++){
                String s = sc.next();
                for(int j=0;j<m;j++){
                    arr[i][j]=(s.charAt(j)=='.')?0:(s.charAt(j)=='#')?1:(s.charAt(j)=='B')?2:3;
                    if(arr[i][j]==3)g++;
                }
            }
            for(int i=0;i<n;i++){
                for(int j=0;j<m;j++){
                        if(arr[i][j]==2){
                            if((i+1<n && (arr[i+1][j]==0||arr[i+1][j]==1))){
                                arr[i+1][j] = 1;
                            }
                            if((i-1>=0 && (arr[i-1][j]==0||arr[i-1][j]==1))){
                                arr[i-1][j] = 1;
                            }
                            if((j+1<m && (arr[i][j+1]==0||arr[i][j+1]==1))){
                                arr[i][j+1] = 1;
                            }
                            if((j-1>=0 && (arr[i][j-1]==0||arr[i][j-1]==1))){
                                arr[i][j-1] = 1;
                            }
                        }
                }
                }
            boolean t = true;

            Queue<Pair> qq = new LinkedList<>();


            boolean[][] v = new boolean[n+1][m+1];
            if(arr[n-1][m-1]==1 && g>0) {
                t = false;
                pw.println("No");
                pw.flush();
                continue;
            }
            if(arr[n-1][m-1]!=1) {
                qq.add(new Pair(n - 1, m - 1));
                v[n - 1][m - 1] = true;
            }
            while(!qq.isEmpty()){
                Pair a =qq.poll();
                if(a.x+1<n && !v[a.x+1][a.y] && arr[a.x+1][a.y]!=1){
                    v[a.x+1][a.y] = true;
                    qq.add(new Pair(a.x+1,a.y));
                }
                if(a.x-1>=0 && !v[a.x-1][a.y] && arr[a.x-1][a.y]!=1){
                    v[a.x-1][a.y] = true;
                    qq.add(new Pair(a.x-1,a.y));
                }
                if(a.y+1<m && !v[a.x][a.y+1] && arr[a.x][a.y+1]!=1){
                    v[a.x][a.y+1] = true;
                    qq.add(new Pair(a.x,a.y+1));
                }
                if(a.y-1>=0 && !v[a.x][a.y-1] && arr[a.x][a.y-1]!=1){
                    v[a.x][a.y-1] = true;
                    qq.add(new Pair(a.x,a.y-1));
                }
            }
           // System.out.println(t);
            for(int i=0;i<n;i++){
                for(int j=0;j<m;j++){
                    if(arr[i][j]==3 && !v[i][j]){
                        t = false;
                    }
                    if(arr[i][j]==2 && v[i][j])
                        t = false;
                }
            }
            pw.println(t?"Yes":"No");
        }
        pw.flush();
        pw.close();
    }
    static class Pair implements Comparable<Pair>{
        int x;
        int y;
        public Pair(int x,int y){
            this.x= x;
            this.y = y;
        }
        public int compareTo(Pair p){
            return Long.compare(this.x,p.x);
        }

    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

        public int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        public long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            String x = next();
            StringBuilder sb = new StringBuilder("0");
            double res = 0, f = 1;
            boolean dec = false, neg = false;
            int start = 0;
            if (x.charAt(0) == '-') {
                neg = true;
                start++;
            }
            for (int i = start; i < x.length(); i++)
                if (x.charAt(i) == '.') {
                    res = Long.parseLong(sb.toString());
                    sb = new StringBuilder("0");
                    dec = true;
                } else {
                    sb.append(x.charAt(i));
                    if (dec)
                        f *= 10;
                }
            res += Long.parseLong(sb.toString()) / f;
            return res * (neg ? -1 : 1);
        }

        public boolean ready() throws IOException {
            return br.ready();

        }
    }
}
