#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define MP make_pair
mt19937 rnd(time(0));
const int MAXN=1e5+5;
int n,m,d[MAXN];
void solve(){
	cin>>n>>m;
	for(int i=1;i<=n;i++) d[i]=0;
	for(int i=1;i<=m;i++){
		int u,v;cin>>u>>v;
		d[u]++;d[v]++;
	}
	if(n<=3) return cout<<"YES"<<endl,void();
	if(n==4&&max({d[1],d[2],d[3],d[4]})==2&&min({d[1],d[2],d[3],d[4]})==2)
			return cout<<"YES"<<endl,void();
	int cnt=0,cntt=0;
	for(int i=1;i<=n;i++) cnt+=(d[i]==n-1),cntt+=(d[i]==n-2);
	if(cnt==1&&m==n-1||cnt==n||cntt==n-1&&m==1ll*(n-1)*(n-2)/2) cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
}
int main(){
	ios::sync_with_stdio(false);
	int _;cin>>_;
	while(_--) solve();
	return 0;
}