#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define y1 shinkle
#define fi first
#define se second
#define bg begin
namespace IO{
#define gc getchar
inline int read(){
    char ch=gc();
    int res=0;bool f=1;
    while(!isdigit(ch))f^=ch=='-',ch=gc();
    while(isdigit(ch))res=(res*10)+(ch^48),ch=gc();
    return f?res:-res;
}
inline ll readll(){
    char ch=gc();
    ll res=0;bool f=1;
    while(!isdigit(ch))f^=ch=='-',ch=gc();
    while(isdigit(ch))res=(res*10)+(ch^48),ch=gc();
    return f?res:-res;
}
inline char readchar(){
	char ch=gc();
	while(isspace(ch))ch=gc();
	return ch;
}
inline int readstring(char *s){
	int top=0;char ch=gc();
	while(isspace(ch))ch=gc();
	while(!isspace(ch)&&ch!=EOF)s[++top]=ch,ch=gc();
	s[top+1]='\0';return top;
}

}
using IO::read;
using IO::readll;
using IO::readchar;
using IO::readstring;
template<typename tp>inline void chemx(tp &a,tp b){(a<b)?(a=b):0;}
template<typename tp>inline void chemn(tp &a,tp b){(a>b)?(a=b):0;}

cs int N=100005;

int n,m;
pii c[N];
void solve(){
	n=read(),m=read();
	int lsta=0,lstb=0,ok=1;
	for(int i=1;i<=m;i++)c[i].fi=read(),c[i].se=read();
	sort(c+1,c+m+1);
	for(int i=1;i<=m;i++){
		if(c[i].fi==c[i-1].fi&&c[i].se!=c[i-1].se)ok=0;
		int a=c[i].fi,b=c[i].se;
		int x=a-lsta;
		
		if(b==lstb+x||(b<=x-1)){
		}
		else ok=0;
		lsta=a,lstb=b;
	}
	if(ok)puts("Yes");
	else puts("No");
}

int main(){
	int T=read();
	while(T--)solve();
	return 0;
}