#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define int long long
typedef long long LL;

inline int read(){
	int x = 0 , f = 1 ; char c = getchar() ;
    while( c < '0' || c > '9' ) { if( c == '-' ) f = -1 ; c = getchar() ; } 
    while( c >= '0' && c <= '9' ) { x = x * 10 + c - '0' ; c = getchar() ; } 
    return x * f ;
}

const int maxn = 1e5+20;
const LL mod = 9982443663;
int n,m,fl;
int l[maxn],r[maxn],sz[maxn];
LL hsh[maxn];
bool vis[maxn],cir[maxn];
vector<int> E[maxn],V[maxn];

void dfs1(int x,int fa){
	r[x] = fa;
	if(vis[x]){
		fl = 1;
		int now = x;
		do{
			cir[now] = 1;
			now = l[now];
		}while(now!=x);
		return ;
	}
	vis[x] = 1;
	for(int y : E[x]){
		if(y==fa) continue;
		l[x] = y;
		dfs1(y,x);
		if(fl) return ;
	}
} 

bool cmp(int a,int b){
	return hsh[a] < hsh[b];
}

void dfs2(int x,int fa){
	if(vis[x]){
//		cout<<"ddd"<<endl;
		fl = 1;
		return ;
	}
	hsh[x] = 0;
//	sz[x] = 1;
	vis[x] = 1;
	for(int y : E[x]){
		if(y==fa) continue;
		if(fa==0 && (y==l[x]||y==r[x])) continue;
		if(cir[y]){
			fl = 1;
			return ;
		}
		V[x].push_back(y);
		dfs2(y,x);
//		sz[x] += sz[y];
		if(fl) return ;
	}
	if(V[x].size()==0) hsh[x] = 1;
	else{
		sort(V[x].begin(),V[x].end(),cmp);
		hsh[x] = 1908537;
		for(int y : V[x]){
			hsh[x] = ((hsh[x] * 91107) ^ hsh[y]) % mod;
		}
	}
}

void solve(){
	n = read();m = read();fl = 0;
	for(int i=1;i<=n;i++) E[i].clear(),V[i].clear();
	for(int i=1;i<=n;i++) l[i] = r[i] = vis[i] = cir[i] = hsh[i] = sz[i] = 0;
	for(int i=1;i<=m;i++){
		int x = read(),y = read();
		E[x].push_back(y);
		E[y].push_back(x);
	} 
	if(m+1==n) puts("YES");
	else if(m >= n + 1) puts("NO");
	else{
		dfs1(1,0);
		fl = 0;
		LL tmp = 0;
		for(int i=1;i<=n;i++) vis[i] = 0;
		for(int i=1;i<=n;i++){
			if(!cir[i]) continue;
			dfs2(i,0);
//			cout<<i<<" "<<hsh[i]<<endl;
			if(!tmp) tmp = hsh[i];
			else if(tmp!=hsh[i]){
				fl = 1;
			}
			if(fl) break;
		}
		if(fl) puts("NO");
		else puts("YES");
	}
}

signed main(){
	//freopen("1.txt","r",stdin);
	int T = 1;
	T = read();
	while(T--) solve();
	return 0;
}

//5 5
//1 2
//2 3
//3 4
//4 1
//1 5