#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;

using ULL = unsigned long long;
const ULL mask = mt19937_64(chrono::steady_clock::now().time_since_epoch().count())();

ULL shift(ULL x) {
    x ^= mask;
    x ^= x << 13;
    x ^= x >> 7;
    x ^= x << 17;
    x ^= mask;
    return x;
}

void solve(){
    int n,m;cin>>n>>m;
    vector<vector<int>>e(n+1);
    vector<int>in(n+1);    
    for(int i=1;i<=m;i++){
        int a,b;cin>>a>>b;
        e[a].push_back(b);
        e[b].push_back(a);
        in[a]++;in[b]++;
    }
    if(m==n-1){
        cout<<"YES\n";return;
    }
    if(m>n){
        cout<<"NO\n";return;
    }

    queue<int>q;
    vector<int>vis(n+1);
    for(int i=1;i<=n;i++){
        if(in[i]==1){
            q.push(i);
        }
    }
    int cnt=n;
    while(not q.empty()){
        int u=q.front();
        q.pop();
        vis[u]=1;cnt--;
        for(int v:e[u]){
            if(!vis[v] and --in[v]==1){
                q.push(v);
            }
        }
    }

    int pre=0,cur=0;
    for(int i=1;i<=n;i++){
        if(!vis[i]){
            cur=i;break;
        }
    }

    vector<vector<int>>g(n+1);
    vector<int>st(n+1);

    auto dfs2=[&](auto &&ff,int u,int fa)->void{
        st[u]=1;
        for(int v:e[u]){
            if(st[v]||vis[v])continue;
            g[u].push_back(v);
            g[v].push_back(u);
            ff(ff,v,u);
        }
    };
    dfs2(dfs2,cur,0);


    vector<ULL>hase(n + 1);
    
    auto get = [&](auto&& ff, int u, int fa)->void {
        for (int v : g[u]) {
            if (v == fa)continue;
            // cout<<u<<"->"<<v<<"\n";
            ff(ff, v, u);
            hase[u] += shift(hase[v]);
        }
    };
    get(get, cur, 0);
    vector<ULL>ha(n + 1);
    ha[cur] = hase[cur];
    auto dfs1 = [&](auto&& ff, int u, int fa)->void {
        for (int v : g[u]) {
            if (v == fa)continue;
            ha[v] = hase[v] + shift(ha[u] - shift(hase[v]));
            ff(ff, v, u);
        }
    };
    dfs1(dfs1, cur, 0);//换根

    // for(int i=1;i<=n;i++){
    //     cout<<ha[i]<<"\n";
    // }
   

    vector<int>h;
    for(int i=1;i<=cnt;i++){
        h.push_back(cur);
        int now=0;
        for(int v:e[cur]){
            if(!vis[v] and v!=pre){
                now=v;break;
            }
        }
        pre=cur;
        cur=now;
    }
    for(int i=0;i+2<cnt;i++){
        int p=i+2;
        if(p>cnt)p-=cnt;
        // cout<<h[i]<<" "<<h[p]<<"\n";
        if(ha[h[i]]!=ha[h[p]]){
            cout<<"NO\n";return;
        }
    }
    cout<<"YES\n";


    // cout<<cnt<<"\n";
    // for(int i=1;i<=n;i++){
    //     cout<<vis[i]<<" ";
    // }
    // cout<<"\n";
}

signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int tt=1;
    cin>>tt;
    while(tt--)
        solve();
    return 0;
}