#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>

template <typename T>
inline void read(T &s)
{
    s=0;int f=1;char ch=getchar();
    for(;ch<'0'||ch>'9';ch=getchar())if(ch=='-')f=-f;
    for(;ch>='0'&&ch<='9';ch=getchar())s=s*10+ch-'0';
    s*=f;
}

#define ll long long
#define ull unsigned ll
#define Vint std::vector<int>

struct Hash
{
    ull h1,h2;
    Hash(){}
    Hash(ull ch):h1(ch),h2(ch){}
    Hash(ull _h1,ull _h2):h1(_h1),h2(_h2){}
    Hash operator +(const Hash &rhs)const{return Hash(h1+rhs.h1,h2+rhs.h2);}
    Hash operator *(const ull &rhs)const{return Hash(h1*rhs,h2*rhs);}
    bool operator ==(const Hash &rhs)const{return h1==rhs.h1&&h2==rhs.h2;}
    bool operator !=(const Hash &rhs)const{return !((*this)==rhs);}
};

const int N=2e6+99;
namespace Pr
{
int cnt,vis[N],prime[N];
void init()
{
    for(int i=2;i<N;i++)
    {
        if(!vis[i])vis[i]=prime[++cnt]=i;
        for(int j=1;j<=cnt;j++)
        {
            if(prime[j]>vis[i]||prime[j]*i>=N)break;
            vis[prime[j]*i]=prime[j];
        }
    }
}
}

Vint G[N],stc;
int vis[N];
int dfs1(int u,int fa)
{
    vis[u]=1;
    for(int v:G[u])
    {
        if(v==fa)continue;
        if(vis[v])return v;
        int ans=dfs1(v,u);
        if(ans)return ans;
    }
    return 0;
}
bool dfs2(int u,int fa)
{
    vis[u]=1;
    for(int v:G[u])
    {
        if(v==fa)continue;
        if(vis[v]||dfs2(v,u))
        {
            stc.push_back(u);
            return 1;
        }
    }
    return 0;
}

Hash F[N];
int Size[N];
void dfs3(int u,int fa)
{
    F[u]=Hash(1);
    Size[u]=1;
    for(int v:G[u])
    {
        if(v==fa||vis[v])continue;
        dfs3(v,u);Size[u]+=Size[v];
        F[u]=F[u]+F[v]*Pr::prime[Size[v]];
    }
}

void work()
{
    int n,m;read(n);read(m);
    for(int u=1;u<=n;u++)G[u].clear(),vis[u]=0;
    for(int i=1;i<=m;i++)
    {
        int u,v;read(u);read(v);
        G[u].push_back(v);
        G[v].push_back(u);
    }
    if(m>n)return puts("NO"),void();
    if(m==n-1)return puts("YES"),void();
    int rt=dfs1(1,0);
    for(int i=1;i<=n;i++)vis[i]=0;
    stc.clear();dfs2(rt,0);
    for(int u=1;u<=n;u++)vis[u]=0;
    for(int u:stc)vis[u]=1;
    for(int u:stc)dfs3(u,0);
    Hash now=F[stc[0]];
    for(int i=1;i<(int)stc.size();i++)
    if(now!=F[stc[i]])return puts("NO"),void();
    puts("YES");
}

int main()
{
    //freopen("_.in","r",stdin);
    Pr::init();
    int T;read(T);
    while(T--)work();
    return 0;
}