#include<bits/stdc++.h>
#define int long long
#define ull unsigned long long
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define x first
#define y second
#define vi vector<int>
#define vpi vector<pii>
#define all(x) (x).begin(),(x).end()
using namespace std;

inline int read()
{
    char c=getchar();int x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}

const int M=1e5+10;
int n,m,deg[M],t[M];
vi e[M];

void solve()
{
    n=read(),m=read();
    for (int i=0;i<=n;i++)deg[i]=0,e[i].clear(),t[i]=0;
    for (int i=1;i<=m;i++)
    {
        int u=read(),v=read();
        e[u].pb(v),e[v].pb(u);
        deg[u]++,deg[v]++;
    }
    for (int i=1;i<=n;i++)
        t[deg[i]]++;
//    for (int i=1;i<=n;i++)cout<<t[i]<<(i==n?'\n':' ');
    int f=-1,f2=-1;
    for (int i=0;i<=n;i++)
        if (t[i]!=0)
        {
            if (t[i]==1)
            {
                if (f2==-1)f2=i;
                else if (f==-1)f=1;
                else return puts("NO"),void();
            }
            else
            {
                if (f==-1)f=1;
                else return puts("NO"),void();
            }
        }
    int tmp=n-1;
//    cout<<"?:"<<f<<' '<<f2<<'\n';
    if (f2!=-1)
    {
        deg[f2]=0;
        for (auto x:e[f2])deg[x]--;
        tmp--;
    }
    if (n<=4)return puts("YES"),void();
    for (int i=1;i<=n;i++)
        if (i!=f&&(deg[i]!=0&&deg[i]!=tmp))return puts("NO"),void();
    puts("YES");
}

signed main()
{
    int T=read();
    while(T--)solve();
    return 0;
}