import java.io.*;
import java.util.*;

public final class hello {
      static int cnt=0,temp[][];
    public static void main(String[] args) throws Exception {
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(java.io.FileDescriptor.out), "ASCII"), 512);        
        FastReader sc = new FastReader();
       int tc=sc.nextInt(),n,m,a[][];
       String s;
       while( tc-->0)
       {
           n=sc.nextInt();
           m=sc.nextInt();
           a=new int[n][m];
           temp=new int[n][m];
           cnt=0;
           for(int i=0;i<n;i++)
           {  s=sc.next();
               for(int j=0;j<m;j++)
               {
                   if(s.charAt(j)=='.')a[i][j]=0;
                   else if(s.charAt(j)=='#')a[i][j]=1;
                   else if(s.charAt(j)=='B')a[i][j]=2;
                   else {a[i][j]=3;cnt++;}
                   temp[i][j]=a[i][j];
               }
           }  
           block_bad(a);
           bfs(a);
           out.write(cnt<=0?"YES\n":"NO\n");
       }
                     
        
        out.flush();
        
    }
    public static void block_bad(int a[][])
    {
        int n=a.length,m=a[0].length;
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<m;j++)
            {
                if(a[i][j]==2)
                {   a[i][j]=1;
                    if(i-1>=0&&a[i-1][j]!=1&&a[i-1][j]!=2)a[i-1][j]=1;
                    if(j+1<m&&a[i][j+1]!=1&&a[i][j+1]!=2)a[i][j+1]=1;
                    if(i+1<n&&a[i+1][j]!=1&&a[i+1][j]!=2)a[i+1][j]=1;
                    if(j-1>=0&&a[i][j-1]!=1&&a[i][j-1]!=2)a[i][j-1]=1;
                }
            }
        }
    }
    public static void bfs(int a[][])
    {
        int n=a.length,m=a[0].length;
        Queue<coord>q=new LinkedList<>();
       if(a[n-1][m-1]==0) q.add(new coord(n-1,m-1));
       else return;
        while(!q.isEmpty())
        {
            int size=q.size();
            while(size-->0)
            {
                coord c=q.poll();
                if(temp[c.x][c.y]==3){cnt--;/*System.out.println("x y is "+c.x+" "+c.y);*/}
                if(c.x-1>=0&&a[c.x-1][c.y]!=1){q.add(new coord(c.x-1,c.y));a[c.x-1][c.y]=1;}
                if(c.x+1<n&&a[c.x+1][c.y]!=1){q.add(new coord(c.x+1,c.y));a[c.x+1][c.y]=1;}
                if(c.y-1>=0&&a[c.x][c.y-1]!=1){q.add(new coord(c.x,c.y-1));a[c.x][c.y-1]=1;}
                if(c.y+1<m&&a[c.x][c.y+1]!=1){q.add(new coord(c.x,c.y+1));a[c.x][c.y+1]=1;}
                a[c.x][c.y]=1;
            }
        }
    }
    static class coord{
        int x,y;
        coord(int x,int y)
        {
            this.x=x;
            this.y=y;
        }
    }

    ///////////////////////////////////////////////////////////////////////////////////
    //////////////////////////////////////////////////////////////////////////////////////////////
    static class FastReader {        
        
        BufferedReader br;        
        StringTokenizer st;        
        
        public FastReader() {            
            br = new BufferedReader(new InputStreamReader(System.in));            
        }        
        
        String next() {            
            while (st == null || !st.hasMoreElements()) {                
                try {                    
                    st = new StringTokenizer(br.readLine());                    
                } catch (IOException e) {                    
                    e.printStackTrace();                    
                }                
            }            
            return st.nextToken();            
        }        
        
        int nextInt() {            
            return Integer.parseInt(next());            
        }        
        
        long nextLong() {            
            return Long.parseLong(next());            
        }        
        
        double nextDouble() {            
            return Double.parseDouble(next());            
        }        
        
        String nextLine() {            
            String str = "";            
            try {                
                str = br.readLine();                
            } catch (IOException e) {                
                e.printStackTrace();                
            }            
            return str;            
        }        
    }
    //////////////////////////////////////////////////////////////////

    static class Reader {        

        final private int BUFFER_SIZE = 1 << 16;        
        private DataInputStream din;        
        private byte[] buffer;        
        private int bufferPointer, bytesRead;        
        
        public Reader() {            
            din = new DataInputStream(System.in);            
            buffer = new byte[BUFFER_SIZE];            
            bufferPointer = bytesRead = 0;            
        }        
        
        public Reader(String file_name) throws IOException {            
            din = new DataInputStream(new FileInputStream(file_name));            
            buffer = new byte[BUFFER_SIZE];            
            bufferPointer = bytesRead = 0;            
        }        
        
        public String readLine() throws IOException {            
            byte[] buf = new byte[1002]; // line length 
            int cnt = 0, c;            
            while ((c = read()) != -1) {                
                if (c == '\n') {
                    break;
                }                
                buf[cnt++] = (byte) c;                
            }            
            return new String(buf, 0, cnt);            
        }        
        
        public int nextInt() throws IOException {            
            int ret = 0;            
            byte c = read();            
            while (c <= ' ') {
                c = read();
            }            
            boolean neg = (c == '-');            
            if (neg) {
                c = read();
            }            
            do {                
                ret = ret * 10 + c - '0';                
            } while ((c = read()) >= '0' && c <= '9');            
            
            if (neg) {
                return -ret;
            }            
            return ret;            
        }        
        
        public long nextLong() throws IOException {            
            long ret = 0;            
            byte c = read();            
            while (c <= ' ') {
                c = read();
            }            
            boolean neg = (c == '-');            
            if (neg) {
                c = read();
            }            
            do {                
                ret = ret * 10 + c - '0';                
            } while ((c = read()) >= '0' && c <= '9');            
            if (neg) {
                return -ret;
            }            
            return ret;            
        }        
        
        public double nextDouble() throws IOException {            
            double ret = 0, div = 1;            
            byte c = read();            
            while (c <= ' ') {
                c = read();
            }            
            boolean neg = (c == '-');            
            if (neg) {
                c = read();
            }            
            
            do {                
                ret = ret * 10 + c - '0';                
            } while ((c = read()) >= '0' && c <= '9');            
            
            if (c == '.') {                
                while ((c = read()) >= '0' && c <= '9') {                    
                    ret += (c - '0') / (div *= 10);                    
                }                
            }            
            
            if (neg) {
                return -ret;
            }            
            return ret;            
        }        
        
        private void fillBuffer() throws IOException {            
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);            
            if (bytesRead == -1) {
                buffer[0] = -1;
            }            
        }        
        
        private byte read() throws IOException {            
            if (bufferPointer == bytesRead) {
                fillBuffer();
            }            
            return buffer[bufferPointer++];            
        }        
        
        public void close() throws IOException {            
            if (din == null) {
                return;
            }            
            din.close();            
        }        
    }    
}
      