#include<bits/stdc++.h>
using namespace std;
#define i64 long long
#define i128 __int128
inline i64 rd()
{
	i64 num=0;char ch=getchar();bool op=0;
	for(;!isdigit(ch);ch=getchar())if(ch=='-')op=1;
	for(;isdigit(ch);ch=getchar())num=num*10+(ch-'0');
	return op?-num:num;
}
inline void pyes(bool ans)
{
	if(ans)printf("YES\n");
	else printf("NO\n");
}

const int m1=998244353,m2=1000000007,m3=1000000009;
inline int Mod(int x,int mod){return x>=mod?x-mod:x;}
inline int ginv(i64 val,int mod){i64 res=1;int p=mod-2;while(p){if(p&1)res=res*val%mod;val=val*val%mod;p>>=1;}return res;}
 
struct H
{
	int L;
	int x,y,z;
	H(){}
	H(int L,int num):L(L),x(num),y(num),z(num){}
	H(int L,int x,int y,int z):L(L),x(x),y(y),z(z){}
};
inline H operator + (const H&A,const H&B){return H(max(A.L,B.L),Mod(A.x+B.x,m1),Mod(A.y+B.y,m2),Mod(A.z+B.z,m3));}
inline H operator * (const H&A,const H&B){return H(A.L+B.L,1ll*A.x*B.x%m1,1ll*A.y*B.y%m2,1ll*A.z*B.z%m3);}
inline bool operator == (const H&A,const H&B){return A.L==B.L&&A.x==B.x&&A.y==B.y&&A.z==B.z;}
inline bool operator < (const H&A,const H&B){return A.L!=B.L?A.L<B.L:(A.x!=B.x?A.x<B.x:(A.y!=B.y?A.y<B.y:A.z<B.z));}

const H B(1,3);
const int N=1e5+10;

H pw[N+N];

int n,m;
vector<int> g[N];
int f[N];
int cA,cB;
bool vis[N];

inline void dfs(int u)
{
	vis[u]=1;
	for(int v:g[u])
	{
		if(f[u]==v)continue;
		if(vis[v]){cA=u,cB=v;continue;}
		f[v]=u,dfs(v);
	}
}
inline H ghsh(int u)
{
	H res(1,1);
	vector<H> ch;
	for(int v:g[u])
		if(v!=f[u]&&!vis[v])
			ch.emplace_back(ghsh(v));
	sort(ch.begin(),ch.end());
	for(H hsh:ch)
		res=res*pw[hsh.L]+hsh;
	res=res*B+H(1,2);
	return res;
}


inline void work()
{
	n=rd(),m=rd();
	for(int i=1;i<=n;i++)vector<int>().swap(g[i]),vis[i]=0,f[i]=0;
	for(int i=1;i<=m;i++)
	{
		int u0=rd(),v0=rd();
		g[u0].emplace_back(v0);
		g[v0].emplace_back(u0);
	}
	if(m<n)return pyes(1);
	if(m>n)return pyes(0);
	
	cA=0,cB=0,dfs(1);
	g[cA].erase(find(g[cA].begin(),g[cA].end(),cB));
	g[cB].erase(find(g[cB].begin(),g[cB].end(),cA));
	
	for(int i=1;i<=n;i++)f[i]=0,vis[i]=0;
	dfs(cA);
	for(int i=1;i<=n;i++)vis[i]=0;
	for(int u=cB;u;u=f[u])vis[u]=1;
	
	vector<H> res;
	for(int u=cB;u;u=f[u])res.emplace_back(ghsh(u));
	
	bool Ans=1;
	for(H hsh:res)Ans&=hsh==res.front();
	pyes(Ans);
}
int main()
{
	n=2e5+10;pw[0]=H(0,1);
	for(int i=1;i<=n;i++)pw[i]=pw[i-1]*B;
	for(int test=rd();test;test--)work();
	return 0;
}