#include<bits/stdc++.h>
using namespace std;
#define M 300005
#define P1 19260817
#define P2 1000000007
#define K1 13448
#define K2 3213458
int n,m,deg[M],sk[M],mk[M],pw1[M],pw2[M];
struct hh{
	int hs1,hs2,sz;
	hh operator+(hh x)const{
		hh a;
		a.hs1=(1ll*hs1*pw1[x.sz]+x.hs1)%P1;
		a.hs2=(1ll*hs2*pw2[x.sz]+x.hs2)%P2;
		a.sz=sz+x.sz;
		return a;
	}
	bool operator!=(hh x)const{
		return hs1!=x.hs1||hs2!=x.hs2||sz!=x.sz;
	}
	bool operator<(hh x)const{
		if(hs1==x.hs1)return hs2<x.hs2;
		return hs1<x.hs1;
	}
}dp[M],now,ac[M],fk[M];
vector<int>d[M];
void init(){
	for(int i=1;i<=n;++i)deg[i]=0,d[i].clear();
}
void dfs(int x,int f){
	for(int i=0;i<(int)d[x].size();++i){
		int v=d[x][i];
		if(mk[v]||v==f)continue;
		dfs(v,x);
	}
	int cnt=0;
	for(int i=0;i<(int)d[x].size();++i){
		int v=d[x][i];
		if(mk[v]||v==f)continue;
		ac[++cnt]=dp[v];
	}
	sort(ac+1,ac+cnt+1);
	dp[x]=(hh){3,3,1};
	for(int i=1;i<=cnt;++i)dp[x]=dp[x]+ac[i];
	dp[x]=dp[x]+(hh){2,2,1};
}
void solve(){
	init();
	scanf("%d%d",&n,&m);
	for(int i=1,x,y;i<=m;++i){
		scanf("%d%d",&x,&y);
		d[x].push_back(y);
		d[y].push_back(x);
		deg[x]++;deg[y]++;
	}
	if(m>n){
		puts("NO");
		return;
	}
	if(m==n-1){
		puts("YES");
		return;
	}
	int cnt=0;
	for(int i=1;i<=n;++i)if(deg[i]==1)sk[++cnt]=i;
	int l=1,r=0;
	while(l<=r){
		int p=sk[l++];
		for(int i=0;i<(int)d[p].size();++i){
			int v=d[p][i];
			deg[v]--;
			if(deg[v]==1)sk[++r]=v;
		}
	}
	for(int i=1;i<=n;++i)mk[i]=deg[i]>=2;
	int sz=0;
	for(int i=1;i<=n;++i)if(mk[i]){
		dfs(i,0);
		fk[++sz]=dp[i];
	}
	for(int i=2;i<=sz;++i){
		if(sk[i]!=sk[1]){
			int f=sz&1;
			for(int j=1;j+2<=sz&&!f;j+=2){
				f|=(fk[j]!=fk[j+2]);
				f|=(fk[j+1]!=fk[j+3]);
			}
			if(f){
				puts("NO");
				return;
			}
			break;
		}
	}
	puts("YES");
}
int main(){
	pw1[0]=pw2[0]=1;
	for(int i=1;i<M;++i)pw1[i]=1ll*K1*pw1[i-1]%P1,pw2[i]=1ll*K2*pw2[i-1]%P2;
	int t;
	scanf("%d",&t);
	while(t--)solve();
}