#include<bits/stdc++.h>

#ifdef DEBUG
#include "debug.h"
#else
#define debug(...) 42
#endif

#define int long long
typedef unsigned long long ull;
const ull mask = std::chrono::steady_clock::now().time_since_epoch().count();
void solve(){
    int n,m;
    std::cin>>n>>m;
    std::vector g(n,std::vector<int>());
    std::vector<int>du(n);
    for(int i=0;i<m;++i){
        int a,b;
        std::cin>>a>>b;
        --a,--b;
        g[a].push_back(b);
        g[b].push_back(a);
        ++du[a];
        ++du[b];
    }
    if(m==n-1){
        std::cout<<"YES\n";
        return;
    }
    if(m>n){
        std::cout<<"NO\n";
        return;
    }
    std::queue<int>q;
    std::vector<int>st(n);
    for(int i=0;i<n;++i){
        if(du[i]==1){
            q.push(i);
        }
    }
    while(!q.empty()){
        int t=q.front();q.pop();
        st[t]=1;
        for(auto &x:g[t]){
            if(--du[x]==1){
                q.push(x);
            }
        }
    }
    auto shift=[&](ull x)->ull {
        x^=mask;
        x^=x<<13;
        x^=x>>7;
        x^=x<<17;
        x^=mask;
        return x;
    };
    auto hash=[&](auto self,int u,int fa)->ull {
        ull res=1;
        for(auto &x:g[u]){
            if(x==fa||!st[x]) continue;
            ull son=self(self,x,u);
            res+=shift(son);
        }
        return res;
    };
    std::vector<ull>tr;
    int sz=std::count(du.begin(),du.end(),2);
    int root=-1;
    for(int i=0;i<n;++i){
        if(!st[i]){
            root=i;
            break;
        }
    }
    int last=-1;
    for(int i=0;i<sz;++i){
        tr.push_back(hash(hash,root,-1));
        for(auto &x:g[root]){
            if(x!=last){
                last=root;
                root=x;
                break;
            }
        }
    }
    sz=tr.size();
    for(int i=0;i<sz;++i){
        if(tr[i]!=tr[(i+2)%sz]){
            std::cout<<"NO\n";
            return;
        }
    }
    std::cout<<"YES\n";
}
signed main(){
    // freopen("in.txt","r",stdin);freopen("out.txt","w",stdout);
    // std::cout<<std::fixed<<std::setprecision(12);
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);std::cout.tie(nullptr);
    int _=1;
    std::cin>>_;
    // clock_t start=clock();
    for(int i=1;i<=_;++i){
        solve();
    }
    // clock_t end=clock();
    // double time=static_cast<double>(end-start)/CLOCKS_PER_SEC;
    // std::cout<<time<<'\n';
    return 0;
}